Lung Cancer

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1. Clinical Overview

Lung cancer remains the leading cause of cancer-related mortality worldwide, accounting for approximately 1.8 million deaths annually. [1] It represents a heterogeneous group of malignancies arising from the bronchial epithelium or alveolar cells, with distinct histological subtypes requiring tailored therapeutic approaches.

The fundamental clinical dichotomy divides lung cancer into:

• Non-Small Cell Lung Cancer (NSCLC) – 85% of cases
• Small Cell Lung Cancer (SCLC) – 15% of cases

This classification has profound therapeutic and prognostic implications, with SCLC characterized by rapid doubling time, early dissemination, and exquisite chemosensitivity, whilst NSCLC exhibits slower growth, later metastasis, and increasing responsiveness to molecularly targeted agents and immunotherapy. [2]

Historical Context and Modern Evolution

The epidemiology of lung cancer has shifted dramatically over the past two decades. While smoking remains the dominant risk factor (responsible for 85-90% of cases), the incidence in never-smokers is rising, particularly among Asian females. [3] These patients frequently harbor targetable driver mutations (EGFR, ALK, ROS1), transforming previously fatal disease into a manageable chronic condition with median survivals exceeding 3-5 years on modern tyrosine kinase inhibitors. [4]

The introduction of immune checkpoint inhibitors (2015 onwards) has revolutionized treatment of advanced NSCLC, with pembrolizumab monotherapy achieving 5-year survival rates of 31.9% in PD-L1 high expressors – unprecedented in metastatic lung cancer. [5]

Key Classification

Clinical Importance

Lung cancer exemplifies the convergence of molecular medicine, surgical oncology, systemic therapy, and palliative care. Key clinical challenges include:

1. Late Presentation: 75% present with advanced (Stage III-IV) disease
2. Heterogeneity: Requires multidisciplinary assessment and genotype-directed therapy
3. Comorbidity: Smoking-related cardiovascular and respiratory disease complicates surgery
4. Rapid Evolution: New targeted agents and biomarkers emerge annually

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2. Epidemiology

Global Burden

Lung cancer is the most commonly diagnosed cancer worldwide (2.2 million new cases in 2020) and the leading cause of cancer death (1.8 million deaths). [1] Incidence varies 20-fold globally, reflecting smoking prevalence and latency periods.

Regional Variation:

• Highest rates: Eastern Asia (China), Eastern Europe, North America
• Rising incidence: Sub-Saharan Africa, South Asia (delayed tobacco epidemic)
• Declining incidence: USA, UK, Australia (smoking cessation programs)

UK-Specific Data

• Incidence: ~48,500 new cases/year (13% of all cancers)
• Mortality: ~35,000 deaths/year (21% of all cancer deaths)
• Age: Median age at diagnosis = 75 years (rare less than 40 years)
• Sex Ratio: Male:Female historically 2:1, now approaching 1:1
• Survival: 1-year survival 45%, 5-year survival 16%, 10-year survival 10% [6]

Risk Factors

Tobacco Smoking (Dominant Risk Factor)

• Attributable Risk: 85-90% of all lung cancer [7]
• Dose-Response: Risk increases with:
  • Pack-years (packs/day × years smoked)
  • Duration of smoking (> 25 years especially high risk)
  • Early age of initiation (less than 15 years)
  • Depth of inhalation
• Relative Risk: 15-30× vs never-smokers (varies by histology)
• Latency: 20-30 years from initiation to diagnosis
• Cessation Benefit: Risk declines after quitting but never returns to baseline
  • 50% reduction after 10 years cessation
  • Approaches (but doesn't reach) never-smoker risk after 20-25 years [7]

Histological Association:

• Squamous and Small Cell: Almost exclusively smokers (> 95%)
• Adenocarcinoma: 40-50% in never-smokers (EGFR+ enriched)

Non-Smoking Risk Factors

Never-Smokers (~10-15% of Lung Cancer)

Distinct clinical entity:

• Predominant Histology: Adenocarcinoma (> 90%)
• Driver Mutations: EGFR (40-60%), ALK (5-10%), ROS1 (1-2%), RET, MET exon 14 [9]
• Demographics: Female, Asian ethnicity, younger age
• Prognosis: Better survival due to targetable mutations

Genetic Susceptibility

Approximately 8% heritability. Genome-wide association studies (GWAS) identify loci on:

• Chromosome 15q25: Nicotinic acetylcholine receptor genes (smoking behavior + direct carcinogenesis)
• Chromosome 5p15: TERT-CLPTM1L locus (telomere maintenance)
• TP53 germline mutations: Li-Fraumeni syndrome (rare)

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3. Pathophysiology

Carcinogenesis Pathway

Lung cancer develops through multi-step accumulation of genetic and epigenetic alterations:

Sequence: Normal Epithelium → Hyperplasia → Metaplasia → Dysplasia → Carcinoma In Situ → Invasive Cancer

Timeline: Typically 20-30 years from initial exposure to clinical diagnosis.

Key Molecular Events

1. Carcinogen Activation

• Tobacco smoke contains > 70 carcinogens (polycyclic aromatic hydrocarbons, nitrosamines, benzene)
• Metabolic activation by CYP1A1 (Cytochrome P450) generates DNA-reactive intermediates
• Benzo[a]pyrene diol epoxide binds guanine → TP53 mutations (G→T transversions at hotspots)

2. DNA Damage and Repair Defects

• Overwhelmed nucleotide excision repair (NER)
• Accumulation of mutations in tumor suppressors (TP53, RB1) and oncogenes (KRAS, EGFR, MYC)

3. Clonal Evolution

• Field cancerization: Entire bronchial tree exposed to carcinogens
• Multiple independent clones → intratumoral heterogeneity → treatment resistance

Molecular Subtypes (NSCLC)

Modern classification integrates histology + molecular drivers. Mutually exclusive driver mutations occur in 50-60% of adenocarcinomas: [10]

Oncogene-Addicted Subtypes (Targetable)

Exam Detail: EGFR Mutations – Deep Dive for Postgraduate Exams

EGFR (Epidermal Growth Factor Receptor) mutations occur in exons 18-21 of the tyrosine kinase domain:

Classic Activating Mutations (90% of EGFR+ cases):

1. Exon 19 deletions (45%): Del E746-A750 most common. Best response to TKIs.
2. Exon 21 L858R (40%): Point mutation. Good response but slightly inferior to exon 19 del.

Other Mutations: 3. Exon 18 G719X (3%): Uncommon, responds to 2nd/3rd gen TKIs. 4. Exon 20 insertions (5-10%): Resistant to standard EGFR TKIs. Require specific inhibitors (amivantamab, mobocertinib). 5. Exon 20 T790M: Acquired resistance mutation (50-60% after 1st/2nd gen TKI progression). Osimertinib is T790M-active.

TKI Generations:

• 1st Gen (Gefitinib, Erlotinib): Reversible binding, median PFS 9-13 months
• 2nd Gen (Afatinib, Dacomitinib): Irreversible binding, median PFS 11-15 months
• 3rd Gen (Osimertinib): T790M-active, CNS-penetrant, median PFS 18.9 months, OS 38.6 months [11]

Current Standard: Osimertinib first-line (FLAURA trial superiority over 1st gen TKIs).

Resistance Mechanisms:

• T790M (50% of 1st/2nd gen failures) → switch to osimertinib
• MET amplification (15-20%) → combination MET + EGFR inhibition
• C797S (osimertinib resistance) → clinical trials
• Histological transformation to SCLC (5%) → chemotherapy

Exam Detail: ALK Rearrangements – Deep Dive

ALK (Anaplastic Lymphoma Kinase) fusions occur via chromosomal rearrangement:

EML4-ALK (most common fusion partner, 70%):

• Inversion on chromosome 2p → fusion gene
• Constitutively active tyrosine kinase
• Mutually exclusive with EGFR/KRAS (different driver)

Clinical Features:

• Young patients (median age 50-55 vs 65 for EGFR)
• Never/light smokers (70-80%)
• Adenocarcinoma with signet ring cells
• Higher propensity for CNS metastases (30-40% at diagnosis)

TKI Generations:

• 1st Gen (Crizotinib): Median PFS 10.9 months, poor CNS penetration
• 2nd Gen (Alectinib, Ceritinib, Brigatinib): CNS-penetrant, median PFS 25-35 months
• 3rd Gen (Lorlatinib): Pan-ALK resistance mutations, median PFS 26 months (in pretreated)

Current Standard: Alectinib first-line (ALEX trial: PFS 34.8 months vs 10.9 months crizotinib) [12]

Resistance Mutations:

• ALK G1202R (most common) → lorlatinib
• ALK I1171T/N, F1174L → lorlatinib
• Bypass pathways (EGFR, KIT amplification) → combination strategies

Detection Methods:

• IHC (screening): Ventana ALK (D5F3) – high sensitivity/specificity
• FISH: Break-apart probe – gold standard confirmation
• NGS: Identifies fusion partner variant

Non-Targetable (Immunotherapy Candidates)

• KRAS non-G12C (20%): No approved targeted therapy. High TMB → responsive to immunotherapy.
• TP53 (50%): Tumor suppressor. Loss permits genomic instability.
• STK11/LKB1 (20%): Predicts poor response to PD-1 inhibitors.
• KEAP1 (10-20%): Confers immunotherapy resistance.

PD-L1 Expression and Tumor Mutational Burden (TMB)

Exam Detail: PD-L1 (Programmed Death-Ligand 1) – Clinical Implementation

Biology:

• PD-L1 expressed on tumor cells and tumor-infiltrating immune cells
• Binds PD-1 on activated T-cells → T-cell exhaustion/anergy → immune evasion
• Adaptive immune resistance mechanism (induced by IFN-γ from infiltrating T-cells)

Detection (IHC Assays):

• 22C3 pharmDx (Dako): Companion diagnostic for pembrolizumab
• 28-8 pharmDx (Dako): Companion diagnostic for nivolumab
• SP263 (Ventana): Companion for durvalumab/atezolizumab
• SP142 (Ventana): Atezolizumab only

Scoring Systems:

1. TPS (Tumor Proportion Score): % of viable tumor cells with membranous PD-L1 staining

   • Used for pembrolizumab, nivolumab
   • TPS ≥50%: "High" expression (25-30% of NSCLC)
   • TPS 1-49%: "Low" expression (30-35%)
   • TPS less than 1%: "Negative" (35-45%)

2. CPS (Combined Positive Score): [PD-L1+ tumor cells + PD-L1+ immune cells] / total viable tumor cells × 100

   • Used for pembrolizumab in certain indications
   • More inclusive (captures immune cell PD-L1)

3. IC (Immune Cell Score): % of tumor area occupied by PD-L1+ immune cells

   • Used for atezolizumab

Clinical Application:

Limitations:

• Spatial heterogeneity: Rebiopsy at different site may yield different result
• Temporal heterogeneity: PD-L1 can change with prior therapy
• Assay variability: Different antibody clones → discordance
• Imperfect predictor: 10-15% with TPS less than 1% respond to pembrolizumab monotherapy; 30-40% with TPS ≥50% don't respond

Alternative/Complementary Biomarkers:

Tumor Mutational Burden (TMB):

• Mutations per megabase (mut/Mb) detected by NGS
• TMB-High: ≥10 mut/Mb (FDA threshold for pembrolizumab 2020)
• Rationale: More mutations → more neoantigens → better immune recognition
• Correlation: Smokers (mean TMB 10 mut/Mb) vs never-smokers (mean 1-2 mut/Mb)
• Predictive: TMB ≥10 predicts response even if PD-L1 negative (CheckMate 227 trial)
• Limitation: Not routinely used outside trials (cost, lack of standardized assay)

Negative Predictive Biomarkers (Immunotherapy Resistance):

• STK11 (LKB1) mutation: Reduced CD8+ T-cell infiltration → poor anti-PD-1 response
• KEAP1 mutation: Often co-occurs with STK11 → "immune desert" phenotype
• EGFR/ALK: Lower TMB, less responsive to immunotherapy (use targeted therapy first)

Viva Scenario: "Why does this patient with high PD-L1 not respond to pembrolizumab?"

• Intrinsic resistance: Absent T-cell infiltration ("cold" tumor), STK11/KEAP1 mutations, defective antigen presentation (B2M loss)
• Acquired resistance: Loss of PD-L1 expression, loss of neoantigens, immune checkpoint upregulation (TIM-3, LAG-3)
• Technical: Wrong biopsy site (heterogeneity), old tissue sample

Small Cell Lung Cancer (SCLC) – Molecular Basis

Neuroendocrine Origin:

• Pulmonary neuroendocrine cells (Kulchitsky cells)
• Express synaptophysin, chromogranin A, CD56

Universal Molecular Features:

• TP53 mutation: > 90% (rapid proliferation)
• RB1 (retinoblastoma) loss: > 90% (cell cycle dysregulation)
• MYC amplification: 20% (extensive-stage disease)
• BCL2 overexpression: Apoptosis resistance

Rapid Doubling Time: 30 days (cf. 180 days for adenocarcinoma)

Early Metastasis: Via hematogenous spread to:

• Brain (40% at presentation)
• Liver (30%)
• Bone (25%)
• Adrenal glands (20%)

Metastatic Routes

Lymphatic Spread (Sequential):

1. Hilar nodes (N1): Peribronchial, interlobar
2. Mediastinal nodes (N2): Ipsilateral mediastinum (stations 2-9)
3. Supraclavicular/Contralateral nodes (N3): Scalene, contralateral mediastinal

Hematogenous Spread:

• Classic sites: Brain, Bone, Liver, Adrenals (mnemonic: B-B-L-A)
• Adrenal metastases often asymptomatic (found on staging CT)
• Bone metastases typically lytic (pathological fracture risk)

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4. Clinical Presentation

Symptom Timeline

Median duration of symptoms before diagnosis: 3-6 months. Subtle onset often leads to delayed presentation.

A. Local (Intrathoracic) Symptoms

Persistent Cough (50-75%)

• New cough in smoker > 40 years or change in chronic smoker's cough (NICE referral criterion)
• Mechanism: Bronchial irritation, obstruction, post-obstructive infection

Haemoptysis (25-50%)

• Urgent CXR indication (NICE: all haemoptysis in smoker > 40 years)
• Ranges from blood-streaked sputum to massive haemoptysis (> 200 mL/24h)
• Mechanism: Tumor neovascularization, bronchial vessel erosion

Dyspnoea (25-40%)

• Multifactorial: Airway obstruction, pleural effusion, phrenic nerve palsy, lymphangitis carcinomatosis, pre-existing COPD

Chest Pain (20-40%)

• Pleuritic: Pleural invasion
• Dull, constant: Chest wall invasion, rib metastases
• Severe, unrelenting: Pancoast tumor with brachial plexus involvement

Wheeze

• Monophonic (single pitch) suggests fixed bronchial obstruction (tumor, foreign body)
• Cf. polyphonic wheeze in COPD/asthma (diffuse small airway narrowing)

Recurrent Pneumonia

• Same lobe repeatedly → suspect post-obstructive pneumonia
• CXR after antibiotic course should show resolution; persistence mandates CT + bronchoscopy

B. Regional Invasion Syndromes

Recurrent Laryngeal Nerve (RLN) Palsy

• Presentation: Hoarseness, weak voice, aspiration risk, "bovine cough" (non-explosive)
• Anatomy: Left RLN more vulnerable (loops under aortic arch)
• Site: Tumors in aorto-pulmonary window or left hilar mass
• Implication: Usually T4 disease (unresectable)

Phrenic Nerve Palsy

• Presentation: Dyspnoea (especially supine), reduced exercise tolerance
• Sign: Elevated hemidiaphragm on CXR/screening
• Diagnosis: Ultrasound or fluoroscopy (paradoxical diaphragm movement on sniff test)

Oesophageal Invasion

• Presentation: Dysphagia, odynophagia
• Diagnosis: CT/endoscopy showing oesophageal compression or fistula
• Stage: T4 (often inoperable)

Superior Vena Cava Obstruction (SVCO)

• Presentation:
  • Facial/neck swelling (worse in morning)
  • Dilated neck/chest wall veins (non-pulsatile, non-compressible)
  • Conjunctival oedema
  • "Pemberton's sign: Raising both arms above head → facial plethora/cyanosis"
• Cause: SCLC (most common), right upper lobe NSCLC
• Management: Oncological emergency → Dexamethasone 8 mg BD + urgent oncology referral (radiotherapy/stent)

Pancoast Tumor (Superior Sulcus Tumor)

• Location: Apex of lung (upper lobe) invading:
  1. T1 nerve root → Pain radiating down ulnar aspect of arm, hand intrinsic muscle wasting (claw hand)
  2. Brachial plexus (C8-T1) → Severe shoulder/arm pain
  3. Stellate ganglion → Horner's Syndrome

Horner's Syndrome (Classic Triad):

1. Ptosis (drooping eyelid) – loss of Müller's muscle innervation
2. Miosis (constricted pupil) – loss of dilator pupillae innervation
3. Anhidrosis (loss of sweating) – ipsilateral face/neck

Additional: Enophthalmos (sunken eye), conjunctival injection

Diagnosis: MRI thoracic inlet (assess T1-T4 vertebral invasion, brachial plexus, subclavian vessels)

Management: Selected cases amenable to chemoradiotherapy + surgical resection (requires en bloc chest wall resection ± vertebrectomy)

C. Metastatic Symptoms

Brain Metastases (30-40% at presentation in SCLC, 10% in NSCLC)

• Headache (worse morning, raised ICP)
• Seizures (focal or generalized)
• Focal neurological deficit (hemiparesis, dysphasia, ataxia)
• Personality change, cognitive decline

Bone Metastases (30-40%)

• Bone pain (back, hips, ribs)
• Pathological fracture (especially vertebrae → spinal cord compression)
• Hypercalcaemia (especially squamous NSCLC)

Liver Metastases (30-40%)

• Often asymptomatic until extensive
• RUQ pain, hepatomegaly
• Jaundice (late, indicates poor prognosis)
• Deranged LFTs (↑ALP, ↑GGT)

Adrenal Metastases (20-30%)

• Usually asymptomatic (bilateral involvement required for adrenal insufficiency)
• Found on staging CT

D. Paraneoplastic Syndromes (10-20%)

Definition: Systemic effects mediated by tumor-secreted hormones, cytokines, or immune cross-reactivity – not direct tumor invasion or metastasis.

Endocrine

Neurological

Lambert-Eaton Myasthenic Syndrome (LEMS)

• Tumor: SCLC (60% of LEMS cases are paraneoplastic)
• Mechanism: Antibodies to presynaptic voltage-gated calcium channels (VGCC) → reduced ACh release
• Presentation:
  • Proximal muscle weakness (legs >arms)
  • Autonomic dysfunction (dry mouth, erectile dysfunction, constipation)
  • Reduced/absent reflexes that augment with repetitive testing (post-tetanic potentiation)
• Diagnosis:
  • "EMG: Low baseline CMAP amplitude, > 100% increment after high-frequency stimulation (cf. Myasthenia Gravis: decremental response)"
  • Anti-VGCC antibodies (P/Q-type) positive
• Treatment: Treat underlying SCLC, 3,4-diaminopyridine (↑ ACh release), immunosuppression

Other Neurological:

• Cerebellar degeneration (Anti-Hu, Anti-Yo)
• Encephalomyelitis
• Sensory neuropathy (Anti-Hu)

Musculoskeletal

Hypertrophic Pulmonary Osteoarthropathy (HPOA) / Pierre-Marie-Bamberger Syndrome

• Tumor: Adenocarcinoma (most common), squamous
• Triad:
  1. Digital clubbing
  2. Periostitis of long bones (tibia, radius, ulna) → painful swollen wrists/ankles
  3. Arthritis (ankles, knees, wrists)
• Mechanism: Unknown (? Vascular endothelial growth factor, ? Platelet-derived growth factor)
• Diagnosis: X-ray shows periosteal reaction (onion-skin appearance)
• Clinical Tip: Wrist pain + clubbing in smoker = lung cancer until proven otherwise

Haematological

• Thrombocytosis (30%): Paraneoplastic IL-6 production → megakaryopoiesis (mild, non-specific)
• Anaemia of Chronic Disease (30%): IL-6 → hepcidin → iron sequestration
• Hypercoagulability (Trousseau Syndrome): Migratory thrombophlebitis, PE/DVT (adenocarcinoma)

Renal

• Nephrotic Syndrome (Membranous Nephropathy): Rare, associated with NSCLC

E. Systemic/Constitutional Symptoms

• Weight Loss (50-70%): > 5% body weight in 6 months (NICE referral criterion)
• Fatigue (60-80%)
• Anorexia (40-60%)
• Cachexia: Multifactorial (cytokines, reduced intake, hypermetabolism)
• Fever: Paraneoplastic (cytokines) or post-obstructive pneumonia

F. Asymptomatic Presentation (10-15%)

• Incidental finding on CXR for other indication
• Detected on lung cancer screening (Low-Dose CT in high-risk populations)

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5. Diagnosis and Investigations

Clinical Pathway Overview

Suspicion (Primary Care) → Urgent CXR (2 weeks) → CT Chest/Abdomen/Pelvis (CTCAP) → Tissue Diagnosis → Staging (PET-CT) → MDT Discussion → Treatment Plan

A. Initial Investigations (Primary Care / Emergency)

Chest X-Ray (CXR) – First-Line

NICE Referral Criteria for Urgent CXR (within 2 weeks):

• Age ≥40 + Unexplained haemoptysis
• Age ≥40 + Smoker/ex-smoker with ≥1:
  • Cough, fatigue, dyspnoea, chest pain, weight loss, appetite loss
• Any age + Persistent/recurrent chest infection, finger clubbing, supraclavicular lymphadenopathy, chest signs consistent with lung cancer, thrombocytosis

CXR Findings Suspicious for Lung Cancer:

• Solitary pulmonary nodule (SPN): "Coin lesion" (less than 3 cm), well-defined
  • "Benign features: Calcification (popcorn, central, laminated), stability > 2 years"
  • "Malignant features: Spiculated margins, eccentric calcification, growth on serial imaging"
• Mass: > 3 cm, ill-defined margins
• Hilar/mediastinal enlargement: Suggests nodal involvement
• Lobar collapse: Secondary to bronchial obstruction
• Pleural effusion: Often bloody (exudative)
• Cavitation: Thick irregular wall (squamous NSCLC)
• Rib destruction: Pancoast tumor, chest wall invasion

Blood Tests:

• FBC: Anaemia (chronic disease), thrombocytosis (paraneoplastic)
• U&E: Hyponatraemia (SIADH), hypercalcaemia (PTHrP)
• LFTs: ↑ALP (bone/liver mets), ↑ALT/GGT (liver mets)
• Calcium (corrected): Hypercalcaemia (squamous NSCLC)
• Serum LDH: Elevated in SCLC (tumor burden marker)

B. Diagnostic Imaging

CT Chest, Abdomen, Pelvis (CTCAP) with IV Contrast

Indications: All patients with CXR suspicious for lung cancer

Provides:

1. Tumor Characterization:
   • Size, location (lobe, segment)
   • Relationship to mediastinum, chest wall, diaphragm
   • Cavitation, calcification, ground-glass opacity
2. Nodal Staging (N):
   • Mediastinal nodes (short-axis diameter > 1 cm suspicious)
   • Stations 1-14 (IASLC lymph node map)
3. Metastatic Survey (M):
   • Liver, adrenal glands
   • Pleural effusion/nodules
   • Abdominal lymphadenopathy

CT Criteria for Malignancy in Pulmonary Nodules:

• Size > 8 mm
• Spiculated/irregular margins
• Upper lobe location
• Growth on serial CT (volume doubling time less than 400 days)
• Part-solid (ground-glass component with solid component)

PET-CT (Fluorodeoxyglucose [FDG] PET)

Indications:

• Staging of potentially curable NSCLC (assesses occult metastases)
• Distinguishes benign vs malignant nodules (SUVmax > 2.5 suspicious)
• Evaluates response to neoadjuvant therapy

Limitations:

• False Positives: Inflammation (TB, sarcoidosis, pneumonia), brown fat
• False Negatives: Bronchoalveolar carcinoma (low metabolic activity), small lesions (less than 8 mm)
• Not routinely used in SCLC (assumes extensive disease)

Brain MRI

Indications:

• All SCLC (40% have brain mets at presentation)
• NSCLC with neurological symptoms
• NSCLC Stage III-IV (20-30% brain mets)

Preferred over CT: Superior sensitivity for small brain metastases

C. Tissue Diagnosis (Essential for Treatment Planning)

"No treatment without histology" – Exceptions: Unfit for biopsy + typical imaging + MDT consensus

Bronchoscopy (Flexible Fibreoptic)

Indications:

• Central tumors (visible endobronchially)
• Hilar masses

Yield:

• Central lesions: 80-90%
• Peripheral lesions: 50-70%

Techniques:

• Endobronchial biopsy: Visible tumor
• Transbronchial biopsy: Peripheral lesions (fluoroscopy-guided)
• Bronchial washings/brushings: Cytology

Complications: Pneumothorax (1-5%), bleeding (less than 1%)

Endobronchial Ultrasound (EBUS-TBNA)

Gold Standard for Mediastinal Staging

Technique:

• Bronchoscope with ultrasound probe
• Real-time visualization of mediastinal/hilar lymph nodes
• Transbronchial needle aspiration (TBNA) of nodes

Yield:

• Sensitivity 89%, Specificity 100% for N2/N3 staging [14]
• Avoids mediastinoscopy in most cases

Stations Accessible: 2R, 2L, 4R, 4L, 7, 10R, 10L, 11R, 11L

CT-Guided Percutaneous Biopsy

Indications:

• Peripheral lesions inaccessible to bronchoscopy
• Pleural-based tumors

Advantages: High yield (85-95%)

Complications: Pneumothorax (15-30%, chest drain required in 5-10%)

Pleural Fluid Aspiration/Pleural Biopsy

Indications: Malignant pleural effusion (exudative, bloody)

Techniques:

• Pleural fluid cytology (60-80% positive if malignant)
• Thoracoscopy (VATS): Direct visualization + biopsy (95% sensitivity)

Mediastinoscopy

Now Largely Replaced by EBUS

Indications:

• EBUS-negative but PET-positive mediastinal nodes (require surgical confirmation)
• Stations not accessible by EBUS (Station 5, 6 anterior mediastinum)

D. Histopathological and Molecular Analysis

Standard Reporting:

1. Histological Type: Adenocarcinoma, squamous, small cell, large cell, NOS
2. Grade: Well/moderately/poorly differentiated (G1-G3)
3. Immunohistochemistry:
   • Adenocarcinoma: TTF-1+, Napsin A+, CK7+
   • Squamous: p40+, CK5/6+
   • SCLC: Synaptophysin+, Chromogranin A+, CD56+

Molecular Testing (Mandatory in Advanced NSCLC Non-Squamous):

Next-Generation Sequencing (NGS) Panel or Individual Assays:

Turnaround Time: 7-14 days (standard), 48-72 hours (urgent, liquid biopsy)

Liquid Biopsy (Circulating Tumor DNA – ctDNA):

• Detect EGFR T790M resistance mutation (post-TKI progression)
• Non-invasive alternative if tissue insufficient
• Monitor treatment response and minimal residual disease

E. Staging Investigations (NSCLC)

Exam Detail: TNM 8th Edition (2017) – Comprehensive Staging Guide

The TNM staging system is the single most important prognostic factor in lung cancer. TNM 8 (introduced 2017) refined tumor size cutoffs based on survival data from 94,708 patients. [26]

T (Primary Tumor) – Size and Invasion

Key Changes in TNM 8:

• T1 subdivided into T1a/b/c (1 cm, 2 cm, 3 cm cutoffs)
• T2 subdivided into T2a/b (4 cm cutoff)
• Size cutoffs now: 1, 2, 3, 4, 5, 7 cm (each 1 cm matters for prognosis)

Clinical Implications:

• T1-2 N0: Surgical candidates (lobectomy/segmentectomy)
• T3: May require extended resection (chest wall, pericardium)
• T4: Often unresectable (mediastinal invasion) → chemoradiotherapy unless isolated ipsilateral lobe nodule

N (Regional Lymph Nodes) – IASLC Lymph Node Map (Stations 1-14)

Nodal Stations (Key Exam Knowledge):

Supraclavicular/Scalene (N3):

• Station 1: Low cervical, supraclavicular, sternal notch nodes

Upper Mediastinal (N2 if ipsilateral, N3 if contralateral):

• Station 2R/2L: Upper paratracheal (above innominate artery)
• Station 3a/3p: Pre-vascular, retro-tracheal (anterior/posterior to trachea)
• Station 4R/4L: Lower paratracheal (below innominate, above azygos/left pulmonary artery)

Aorto-pulmonary (N2):

• Station 5: Subaortic (aorto-pulmonary window)
• Station 6: Para-aortic (ascending aorta/phrenic nerve)

Subcarinal (N2):

• Station 7: Subcarinal (below carina) – most commonly involved mediastinal node

Lower Mediastinal (N2):

• Station 8: Paraesophageal (adjacent to esophagus)
• Station 9: Pulmonary ligament

Hilar/Interlobar (N1):

• Station 10: Hilar (main bronchus)
• Station 11: Interlobar (between lobes)

Peripheral (N1):

• Station 12: Lobar (lobar bronchi)
• Station 13: Segmental
• Station 14: Subsegmental

N Categories:

Clinical Significance:

• N0-1: Surgical ± adjuvant chemotherapy
• N2 (single-station, microscopic): Neoadjuvant chemo → surgery (selected cases)
• N2 (multi-station, bulky): Definitive concurrent chemoradiotherapy (PACIFIC protocol)
• N3: Unresectable → CRT or systemic therapy

M (Distant Metastasis)

TNM 8 Innovation: M1a/b/c Substaging

• Recognizes prognostic heterogeneity in Stage IV
• M1b (oligometastatic): May benefit from local ablative therapy (SBRT to primary + metastasis) + systemic therapy
• M1c (polymetastatic): Systemic therapy only

Stage Grouping (TNM 8) – Complete Table:

Exam Viva Question: "What has changed in TNM 8 compared to TNM 7?"

Answer:

1. T Category: Refined size cutoffs (1, 2, 3, 4, 5, 7 cm). T1 now T1a/b/c, T2 now T2a/b.
2. M Category: M1 subdivided into M1a (thoracic), M1b (single extrathoracic), M1c (multiple extrathoracic).
3. Stage Shifts:
   • T2b N0 moved from IIA to IIA (no change)
   • T3 N0 moved from IIB to IIB (but now includes 5-7 cm size criterion)
   • M1a now Stage IVA (was Stage IV)
4. Survival Data: Based on 94,708 patients from IASLC database (1999-2010). More granular prognostication.

F. Staging Investigations (SCLC)

Veterans Administration (VA) Classification (Still Widely Used):

1. Limited-Stage (LS-SCLC): Confined to one hemithorax + regional lymph nodes (can be encompassed in single radiotherapy port)
   • Approx. 30% at diagnosis
   • Median survival: 15-20 months
2. Extensive-Stage (ES-SCLC): Beyond one hemithorax (metastatic)
   • Approx. 70% at diagnosis
   • Median survival: 8-13 months

Modern Approach: TNM staging increasingly used (same as NSCLC) for uniformity

Staging Workup (SCLC):

• CT Chest/Abdomen/Pelvis
• Brain MRI (mandatory – 40% have brain mets)
• Bone scan or PET-CT (if symptomatic bone pain)

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6. Management

Performance Status Assessment

Exam Detail: ECOG Performance Status – Critical for Treatment Decisions

Performance status (PS) is a standardized measure of functional capacity that profoundly influences treatment selection, tolerance, and prognosis. [27]

ECOG (Eastern Cooperative Oncology Group) Scale (0-4):

Alternative: Karnofsky Performance Status (KPS, 0-100% scale) – used in neuro-oncology and older US trials

Correlation:

• ECOG 0 = KPS 90-100%
• ECOG 1 = KPS 70-80%
• ECOG 2 = KPS 50-60%
• ECOG 3 = KPS 30-40%
• ECOG 4 = KPS 10-20%

Clinical Significance:

1. Surgical Candidacy: ECOG 0-1 preferred. ECOG 2 only for limited resection if compelling (e.g., early-stage, no other options).

2. Chemotherapy Eligibility:

   • ECOG 0-1: Standard-dose platinum doublet
   • ECOG 2: Carboplatin preferred over cisplatin (less nephrotoxic, less emetogenic). Consider dose reduction or single-agent therapy.
   • ECOG 3-4: Chemotherapy likely harmful (toxicity > benefit). Focus on symptom control.

3. Immunotherapy:

   • ECOG 0-2: Checkpoint inhibitors (pembrolizumab, nivolumab, atezolizumab) approved and beneficial
   • ECOG ≥3: Not studied in trials, likely ineffective (requires functional immune system)

4. Prognostic Impact (Stage IV NSCLC, best supportive care):

   • ECOG 0: Median survival 9-12 months
   • ECOG 1: Median survival 6-9 months
   • ECOG 2: Median survival 3-6 months
   • ECOG 3: Median survival 1-3 months
   • ECOG 4: Median survival less than 1 month

Exam Tip: Always assess and document PS in lung cancer viva. It determines who gets treated, how aggressively, and with what modality.

Multidisciplinary Team (MDT) Approach

All lung cancer cases discussed at MDT comprising:

• Respiratory physician
• Medical oncologist
• Thoracic surgeon
• Clinical oncologist (radiotherapy)
• Radiologist
• Pathologist
• Lung cancer nurse specialist
• Palliative care

Key Decisions:

1. Curative vs palliative intent
2. Surgery vs radiotherapy vs systemic therapy
3. Sequencing of modalities (neoadjuvant, adjuvant, concurrent)

A. Non-Small Cell Lung Cancer (NSCLC) – Stage-Specific Management

Stage I-II (Localized Disease – 15-20% at Diagnosis)

First-Line: Surgical Resection

Pre-Operative Assessment:

1. Fitness for Surgery:
   • ECOG Performance Status 0-1 preferred
   • Cardiopulmonary Risk: Echo, ECG, CPET (Cardiopulmonary Exercise Testing)
2. Lung Function (Spirometry):
   • Pre-operative FEV1 > 1.5 L (for lobectomy)
   • Predicted post-operative FEV1 > 40% (or > 800 mL)
   • DLCO (diffusing capacity) > 40%

Surgical Options:

Adjuvant Chemotherapy (Improves Survival by 5%):

• Indication: Stage IB (tumor > 4 cm), Stage II-IIIA (all cases)
• Regimen: Platinum doublet (Cisplatin + Vinorelbine or Pemetrexed) × 4 cycles
• Benefit: 5-year survival improvement from 60% to 65% (Stage IB-II) [16]

Adjuvant Osimertinib (EGFR+ Only):

• ADAURA Trial: Osimertinib × 3 years post-resection for EGFR-mutant Stage IB-IIIA → 89% disease-free survival at 3 years (vs 52% placebo) [17]
• Now standard of care for resected EGFR+ NSCLC

Alternative to Surgery: Stereotactic Ablative Radiotherapy (SABR/SBRT)

Indications:

• Medically inoperable (poor lung function, cardiac comorbidity)
• Patient refusal of surgery
• Peripheral tumors T1-2 N0

Technique:

• High-dose radiotherapy (54-60 Gy in 3-8 fractions)
• Image-guided, highly conformal
• Targets tumor with 5 mm margin

Outcomes:

• Local control: 85-95% at 3 years
• 3-year survival: 55-60% (comparable to surgery in selected patients) [18]

Complications: Radiation pneumonitis (5-10%), chest wall pain (10-20%)

Stage III (Locally Advanced – 30-35% at Diagnosis)

Heterogeneous group requiring individualized approach.

Stage IIIA (Resectable N2):

Approach 1: Neoadjuvant Chemotherapy → Surgery → Adjuvant Chemotherapy

• Downstage tumor
• Test chemosensitivity
• Treat micrometastases early

Approach 2: Concurrent Chemoradiotherapy → Durvalumab Consolidation (PACIFIC Protocol)

• For unresectable Stage IIIA-C
• See below

Stage IIIB-C (Unresectable):

PACIFIC Protocol (Standard of Care):

1. Concurrent Chemoradiotherapy:
   • Radiotherapy: 60-66 Gy in 30-33 fractions
   • Chemotherapy: Platinum doublet (Cisplatin/Carboplatin + Etoposide or Paclitaxel)
2. Consolidation Durvalumab (PD-L1 inhibitor):
   • 10 mg/kg IV every 2 weeks × 12 months
   • Started 1-42 days post-CRT

PACIFIC Trial Results:

• Median PFS: 16.8 months (durvalumab) vs 5.6 months (placebo)
• 4-year OS: 49.6% vs 36.3% [19]

Transformed Stage III NSCLC outcomes – previously dismal (less than 15% 5-year survival) now approaching 50% with PACIFIC protocol.

Stage IV (Metastatic Disease – 50-60% at Diagnosis)

Treatment Algorithm Based on Molecular Subtype:

A. Driver Mutation Positive (EGFR/ALK/ROS1/BRAF/MET/RET/NTRK/KRAS G12C)

First-Line: Targeted Therapy (Oral Tyrosine Kinase Inhibitors)

Resistance Mechanisms:

• EGFR T790M (50%): Switch to osimertinib (3rd generation, T790M-active)
• ALK G1202R: Switch to lorlatinib (3rd generation)
• MET amplification, BRAF V600E, PIK3CA mutations: Combination strategies under investigation

B. Driver Mutation Negative / PD-L1 Expression ≥50%

First-Line: Pembrolizumab Monotherapy

• KEYNOTE-024: Pembrolizumab vs chemotherapy in PD-L1 TPS ≥50% → 5-year OS 31.9% vs 16.3% [5]
• Regimen: 200 mg IV every 3 weeks (or 400 mg every 6 weeks) × 2 years or progression

C. Driver Mutation Negative / PD-L1 1-49% OR Any PD-L1 with High Tumor Burden

First-Line: Chemo-Immunotherapy

• Non-Squamous: Pembrolizumab + Carboplatin/Cisplatin + Pemetrexed
• Squamous: Pembrolizumab + Carboplatin + Paclitaxel/nab-Paclitaxel
• KEYNOTE-189 (Non-Squamous): Median OS 22.0 months (combo) vs 10.7 months (chemo alone) [20]

D. Driver Mutation Negative / PD-L1 less than 1% (PD-L1 Negative)

First-Line: Platinum Doublet Chemotherapy

Alternative: Chemo-Immunotherapy (Pembrolizumab + chemo) still superior to chemo alone even in PD-L1 less than 1%

Second-Line Options:

• Docetaxel ± Ramucirumab (VEGF inhibitor)
• Nivolumab, Pembrolizumab, Atezolizumab (if not used first-line)

B. Small Cell Lung Cancer (SCLC) Management

Principle: SCLC is disseminated at diagnosis (even if "limited-stage"). Surgery rarely indicated.

Limited-Stage SCLC (LS-SCLC)

Standard: Concurrent Chemoradiotherapy

Chemotherapy:

• Cisplatin 75 mg/m² Day 1 + Etoposide 100 mg/m² Days 1-3 every 3 weeks × 4 cycles
• Alternative: Carboplatin AUC 5-6 (if renal impairment)

Radiotherapy:

• Concurrent (started with Cycle 1 or 2) superior to sequential
• Dose: 60-66 Gy in 30-33 fractions (once-daily) OR 45 Gy in 30 fractions (twice-daily)
• Target: Primary tumor + involved nodes

Outcome:

• Median survival: 18-24 months
• 5-year survival: 20-25%

Prophylactic Cranial Irradiation (PCI):

• Indication: All LS-SCLC patients achieving complete/partial response to chemoradiotherapy
• Rationale: Brain is sanctuary site (40% develop brain mets within 2 years)
• Dose: 25 Gy in 10 fractions
• Benefit: Reduces brain metastasis incidence from 40% to 15%, improves 3-year survival from 15% to 21% [21]
• Toxicity: Neurocognitive decline (controversial in extensive-stage, see below)

Extensive-Stage SCLC (ES-SCLC)

First-Line: Chemotherapy + Immunotherapy

Standard (2020 Onwards): Atezolizumab + Carboplatin + Etoposide

• IMpower133 Trial: Median OS 12.3 months (combo) vs 10.3 months (chemo alone) [22]
• Regimen:
  • Atezolizumab 1200 mg IV Day 1
  • Carboplatin AUC 5 Day 1
  • Etoposide 100 mg/m² Days 1-3
  • Every 3 weeks × 4 cycles, then atezolizumab maintenance until progression

Alternative: Durvalumab + Carboplatin + Etoposide (CASPIAN Trial)

PCI in ES-SCLC:

• Controversial – No OS benefit demonstrated, significant neurocognitive toxicity
• Current Practice: Offer if good response to chemotherapy + patient counseled on risks

Relapsed/Refractory SCLC:

• Platinum-Sensitive (relapse > 6 months): Re-challenge with cisplatin/carboplatin + etoposide
• Platinum-Resistant (relapse less than 6 months): Topotecan, lurbinectedin, CAV (cyclophosphamide + doxorubicin + vincristine)
• Prognosis: Very poor (median survival 4-6 months)

C. Supportive and Palliative Care

Integral to Lung Cancer Management at All Stages

Early Palliative Care Integration:

• Improves quality of life
• Reduces depression
• Paradoxically prolongs survival (median +2.7 months in metastatic NSCLC) [23]
• Should be introduced at diagnosis (not "end-of-life care")

Symptom Management

Dyspnoea:

• Opioids (morphine 2.5-5 mg PO PRN/regular)
• Benzodiazepines (lorazepam 0.5 mg PRN for anxiety)
• Oxygen (if hypoxic, SpO₂ less than 92%)
• Airway stenting (endobronchial obstruction)
• Thoracentesis ± pleurodesis (malignant effusion)

Cough:

• Simple linctus, codeine
• Treat underlying cause (infection, effusion, GERD)

Haemoptysis:

• Massive haemoptysis (> 200 mL/24h): Medical emergency
  • Resuscitation, crossmatch, consider bronchial artery embolization, palliative radiotherapy
• Minor: Tranexamic acid 1 g TDS PO

Pain:

• WHO analgesic ladder
• Bone metastases: NSAIDs + palliative radiotherapy ± bisphosphonates/denosumab
• Neuropathic (Pancoast): Gabapentin, pregabalin, amitriptyline
• Severe pain: Opioid rotation, methadone, interventional (nerve block, spinal analgesia)

Anorexia-Cachexia:

• Nutritional support (dietician)
• Appetite stimulants: Megestrol acetate, corticosteroids (short-term)
• Emerging: Anamorelin (ghrelin agonist, not widely available)

SVCO:

• Dexamethasone 8 mg BD (reduce vasogenic oedema)
• Elevate head of bed
• Urgent radiotherapy (SCLC, sensitive NSCLC) or stenting (prompt relief)

Spinal Cord Compression:

• Oncological Emergency
• Dexamethasone 16 mg STAT, then 8 mg BD
• Urgent MRI whole spine
• Radiotherapy ± surgical decompression (if single level, good prognosis)

Brain Metastases:

• Solitary/Oligometastatic (less than 4 lesions): Stereotactic radiosurgery (SRS) or surgical resection
• Multiple: Whole-brain radiotherapy (WBRT) – palliative, neurocognitive toxicity
• Symptomatic: Dexamethasone 4-8 mg BD (reduce oedema), anticonvulsants if seizures

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7. Screening and Prevention

Lung Cancer Screening

Exam Detail: Low-Dose CT (LDCT) Screening – Evidence and Implementation

Rationale: Detect lung cancer at early stage (I-II) when curable with surgery (5-year survival 60-90% vs 10-15% for advanced disease)

Landmark Trials

1. NLST (National Lung Screening Trial, USA, 2011)

• Population: 53,454 high-risk (age 55-74, ≥30 pack-years, current/quit less than 15 years)
• Intervention: Low-Dose CT (LDCT) vs CXR annually × 3 years
• Results:
  • 20% reduction in lung cancer mortality with LDCT
  • 6.7% reduction in all-cause mortality
  • "Number needed to screen to prevent 1 lung cancer death: 320 [24]"

2. NELSON Trial (Netherlands/Belgium, 2020)

• Population: 15,792 high-risk (age 50-74, > 10 cigarettes/day × > 30 years or > 15 cigarettes/day × > 25 years)
• Intervention: LDCT at 1, 2, 4, 6.5 years vs no screening
• Results:
  • 24% reduction in lung cancer mortality in men at 10 years
  • 33% reduction in women (higher than men, possibly due to higher susceptibility to tobacco)
  • 11% reduction in all-cause mortality [25]

Current Screening Recommendations

USPSTF (2021 Guidelines):

• Age 50-80 years (lowered from 55 in 2013)
• ≥20 pack-year smoking history (lowered from 30)
• Current smoker or quit within 15 years
• Annual LDCT until age 80 or quit smoking > 15 years

UK NHS Targeted Lung Health Check Programme (2019-):

• Rolling out nationally (pilot sites: Manchester, Liverpool, Leeds)
• Age 55-74, ever-smokers
• Risk-stratified approach: LDCT offered based on individual risk (PLCOm2012 model incorporating age, smoking, family history, medical history)
• Target: 40% uptake in eligible population

Canada (2022):

• Age 55-74, ≥20 pack-years, current/quit less than 15 years
• Annual or biennial LDCT (provincial variation)

Australia:

• Currently no national screening program
• Royal Australian College of GPs recommends case-by-case discussion

LDCT Protocol

Technical Parameters:

• Radiation Dose: 1-2 mSv per scan (cf. diagnostic chest CT 7-8 mSv, CXR 0.02 mSv)
• Slice Thickness: ≤2.5 mm (nodule detection)
• Contrast: None (unless suspicious finding requiring diagnostic CT)

Nodule Management (Lung-RADS v1.1 Classification):

Benefits vs Harms

Benefits:

• 20-24% lung cancer mortality reduction (NLST, NELSON)
• 6-11% all-cause mortality reduction (earlier detection of other smoking-related diseases)
• Stage shift: 63% of screen-detected cancers are Stage I (vs 20% in symptomatic presentation)

Harms:

1. False Positives (96% of nodules detected are benign):

   • Frequency: 39% have positive screen (Lung-RADS 3-4) in first round, 96% are false positive
   • Consequences: Anxiety, repeat CT scans (radiation), invasive procedures (biopsy, surgery)
   • Mitigation: Lung-RADS classification reduces false positives vs NLST criteria

2. Overdiagnosis (detection of indolent cancers that would never cause harm):

   • Estimate: 10-20% of screen-detected lung cancers
   • Mechanism: Slow-growing adenocarcinomas (lepidic-predominant, ground-glass opacities)
   • Consequence: Unnecessary surgery/treatment

3. Radiation Exposure:

   • Cumulative Risk: 20 annual LDCTs = 20-40 mSv (equivalent to 2-4 diagnostic CTs)
   • Theoretical Cancer Risk: Negligible (1 in 2500 fatal cancers induced by lifetime screening)
   • Benefit >> Harm: 1 cancer prevented for every 320 screened vs 1 induced per 2500 screened

4. Incidental Findings (20-30%):

   • Coronary artery calcification, emphysema, interstitial lung disease, aortic aneurysm
   • May require further investigation (cost, anxiety)
   • Benefit: Early detection of cardiovascular disease (leading cause of death in smokers)

Cost-Effectiveness:

• NLST: $81,000 per quality-adjusted life year (QALY) gained (below $100,000 threshold)
• UK Pilot: £8,466 per QALY (cost-effective by NICE threshold £20,000-30,000/QALY)

Barriers to Implementation:

• Smoker stigma (reluctance to present)
• Access to CT scanners (rural/underserved areas)
• Radiology workforce (reporting workload)
• Smoking cessation integration (screening is "teachable moment")

Exam Viva Question: "Why is LDCT screening not recommended for never-smokers despite 10-15% of lung cancer occurring in never-smokers?"

Answer:

• Low Absolute Risk: Never-smokers have baseline lung cancer risk ~0.2% lifetime vs 15-20% in heavy smokers
• Number Needed to Screen: Would need to screen thousands to prevent 1 death (not cost-effective)
• False Positive Rate: 96% of nodules are benign → high anxiety/investigation burden in low-risk population
• Alternative: Case-by-case shared decision-making for never-smokers with strong family history or occupational exposure (asbestos, radon)

Prevention

Smoking Cessation (Single Most Effective Intervention):

• Advice: Brief intervention (less than 3 min) increases quit rate by 2%
• Pharmacotherapy:
  • "Nicotine replacement therapy (NRT): Patches, gum, lozenges (doubles quit rate)"
  • "Varenicline (Champix): Partial nicotinic agonist (triples quit rate)"
  • "Bupropion (Zyban): Antidepressant (doubles quit rate)"
• Behavioral Support: Counseling + pharmacotherapy (15-25% sustained abstinence at 1 year)

Policy Interventions:

• Taxation (10% price increase → 4% consumption reduction)
• Smoke-free legislation (public places)
• Plain packaging, graphic warnings
• Advertising bans

Occupational Hygiene:

• Asbestos abatement (mesothelioma latency 20-40 years)
• Silica exposure control (mining, construction)

Dietary/Chemoprevention:

• No Evidence for β-carotene, vitamin E (CARET trial showed harm)
• Healthy diet, physical activity: General cancer risk reduction

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8. Prognosis and Outcomes

Overall Survival

Lung Cancer (All Stages Combined):

• 1-year survival: 45%
• 5-year survival: 16%
• 10-year survival: 10% [6]

Worst prognosis of common cancers (cf. breast 87%, prostate 85%, colorectal 60% 5-year survival)

Stage-Specific Survival (NSCLC, TNM 8)

Key Principle: Stage is the strongest prognostic factor.

Histology-Specific Survival

NSCLC:

• Adenocarcinoma: Best prognosis (median survival Stage IV: 12-18 months with modern therapy)
• Squamous: Intermediate (median survival Stage IV: 9-12 months)
• Large Cell: Worst NSCLC subtype (median survival Stage IV: 6-9 months)

SCLC:

• Limited-Stage: Median survival 18-24 months, 5-year survival 20-25%
• Extensive-Stage: Median survival 10-13 months (with immunotherapy), 5-year survival less than 5%

Molecular Subtype Impact

EGFR-Mutant NSCLC (Stage IV):

• Median OS with osimertinib: 38.6 months [11]

ALK-Positive NSCLC (Stage IV):

• Median OS with alectinib: Not reached at 5 years (~50% alive) [12]

PD-L1 High (≥50%) NSCLC (Stage IV):

• Median OS with pembrolizumab monotherapy: 26.3 months, 5-year survival 31.9% [5]

Transformation from Uniformly Fatal (Median OS 4-6 Months in 1970s) to Manageable Chronic Disease in Molecular Subgroups

Performance Status (ECOG) as Prognostic Factor

ECOG ≥2: Chemotherapy often not beneficial (toxicity >benefit). Focus on best supportive care.

Factors Predicting Poor Prognosis

• SCLC histology
• Extensive-stage disease (M1)
• Poor performance status (ECOG ≥2)
• Weight loss > 10% in 6 months
• Male sex
• Age > 70 years (comorbidity, reduced tolerance to therapy)
• Elevated LDH (tumor burden marker)
• Anemia (Hb less than 10 g/dL)
• Hypercalcemia
• Liver metastases (worse than bone/brain)
• STK11/KEAP1 co-mutations (immunotherapy resistance)

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9. Complications

Treatment-Related Complications

Post-Surgical:

• Respiratory Failure: Especially post-pneumonectomy (↓ lung reserve)
• Arrhythmia: Atrial fibrillation (20-30% post-lobectomy/pneumonectomy)
• Air Leak: Prolonged (> 5 days) in 10-15%
• Empyema: Infected pleural space (1-3%)
• Bronchopleural Fistula: Communication between bronchus and pleural space (1-2%, higher post-pneumonectomy)

Chemotherapy:

• Myelosuppression: Neutropenic sepsis (febrile neutropenia), anemia, thrombocytopenia
• Nausea/Vomiting: Cisplatin highly emetogenic (antiemetics essential)
• Peripheral Neuropathy: Platinum agents, taxanes (dose-limiting)
• Renal Toxicity: Cisplatin (require pre-/post-hydration, monitor Cr)
• Ototoxicity: Cisplatin (high-frequency hearing loss)

Radiotherapy:

• Radiation Pneumonitis (5-15%):
  • "Onset: 4-12 weeks post-RT"
  • "Symptoms: Dry cough, dyspnoea, low-grade fever"
  • "CT: Ground-glass opacification in radiation field"
  • "Treatment: Prednisolone 0.5-1 mg/kg"
• Radiation Fibrosis: Late (> 6 months), irreversible
• Oesophagitis: Concurrent CRT (dysphagia, odynophagia) – analgesia, nutritional support

Immunotherapy (Immune-Related Adverse Events – irAEs):

• Pneumonitis (3-5%): Ground-glass on CT, dyspnoea → stop immunotherapy, high-dose steroids
• Colitis (2-3%): Diarrhea, blood PR → stop, steroids ± infliximab
• Hepatitis (1-2%): ↑ALT/AST → stop, steroids
• Endocrinopathies: Hypothyroidism (10%), hypophysitis (less than 1%), type 1 diabetes (less than 1%)
• Dermatitis: Rash, pruritus (20-30%) – topical steroids, antihistamines

Targeted Therapy (TKIs):

• Diarrhea: EGFR inhibitors (20-30%) – loperamide
• Rash: EGFR inhibitors (50-80%) – acneiform, face/chest – doxycycline, topical steroids
• Hypertension: ALK inhibitors (20-30%) – antihypertensives
• Hepatotoxicity: ALK inhibitors (↑ALT) – monitor LFTs
• Interstitial Lung Disease (ILD): Osimertinib (3%) – stop drug, steroids

Disease-Related Complications

Superior Vena Cava Obstruction (SVCO):

• See Section 4 (Clinical Presentation)

Spinal Cord Compression:

• See Section 6C (Palliative Care)

Malignant Pleural Effusion:

• Dyspnoea, reduced exercise tolerance
• Diagnosis: Exudative effusion (Light's criteria), positive cytology
• Management: Therapeutic thoracentesis (symptom relief) → pleurodesis (talc) or indwelling pleural catheter (if life expectancy > 3 months)

Pericardial Effusion/Tamponade:

• Beck's triad: Hypotension, muffled heart sounds, elevated JVP
• Emergency: Pericardiocentesis ± pericardial window

Post-Obstructive Pneumonia:

• Recurrent pneumonia same lobe → bronchial obstruction (tumor, mucus plug)
• Treat infection, then investigate with bronchoscopy

Cachexia:

• Multifactorial (cytokines, reduced intake, hypermetabolism)
• Associated with poor prognosis
• Limited effective treatments (see Section 6C)

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10. Follow-Up and Surveillance

Post-Curative Treatment (Stage I-III NSCLC After Surgery/Radiotherapy)

Purpose: Detect recurrence early (potentially salvageable) and monitor for second primary lung cancers (field cancerization)

NICE/ASCO Recommendations:

• History and Examination: Every 3-6 months × 2 years, then annually
• CT Chest (Low-Dose): 6-12 monthly × 2 years, then annually × 3-5 years
• CXR: Not recommended (low sensitivity for recurrence)

No Role for Routine PET-CT or Tumor Markers (CEA, CYFRA 21-1) in Asymptomatic Patients

Recurrence Patterns:

• Local (20-30%): May be amenable to salvage surgery/SABR
• Distant (50-70%): Systemic therapy

Second Primary Lung Cancers:

• Risk: 1-2% per year (field cancerization)
• Higher in continued smokers

Advanced/Metastatic Disease (Stage IV)

Active Treatment Phase:

• Clinical Assessment: Every 3-4 weeks (at time of systemic therapy)
• CT Staging Scans: Every 6-12 weeks (assess response per RECIST criteria)
• Blood Tests: FBC, U&E, LFTs (toxicity monitoring)

Stable Disease on Maintenance Therapy:

• CT Scans: Every 3 months
• Clinical Assessment: Monthly (or as needed)

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11. Key Guidelines and Evidence

International Guidelines

1. NICE NG122 (2019): Lung cancer: diagnosis and management

   • UK standard for referral, diagnosis, staging, treatment pathways

2. NCCN Guidelines (2025): Non-Small Cell Lung Cancer

   • Comprehensive, updated 3-4 times/year, molecular algorithm

3. ESMO Clinical Practice Guidelines (2020): Metastatic NSCLC

   • European consensus on systemic therapy

4. ASCO Guidelines (2020): Systemic Therapy for Stage IV NSCLC

   • Evidence-based recommendations for molecular testing and treatment sequencing

Landmark Trials

Screening:

• NLST (2011): LDCT reduces lung cancer mortality by 20% [24]
• NELSON (2020): LDCT reduces mortality by 24% (men), 33% (women) [25]

Surgery:

• LACE-Bio (2013): Adjuvant chemotherapy improves 5-year survival by 5% in Stage IB-III [16]
• ADAURA (2020): Adjuvant osimertinib in EGFR+ Stage IB-IIIA → 89% DFS at 3 years [17]

Radiotherapy:

• RTOG 0618 (2015): SABR achieves 3-year local control 88% in T1-2 N0 [18]

Immunotherapy:

• KEYNOTE-024 (2019): Pembrolizumab monotherapy in PD-L1 ≥50% → 5-year OS 31.9% [5]
• KEYNOTE-189 (2019): Pembrolizumab + chemo (non-squamous) → median OS 22 months [20]
• PACIFIC (2018): Durvalumab consolidation post-CRT (Stage III) → 4-year OS 49.6% [19]
• IMpower133 (2019): Atezolizumab + chemo (ES-SCLC) → median OS 12.3 months [22]

Targeted Therapy:

• FLAURA (2020): Osimertinib (EGFR+) → median OS 38.6 months [11]
• ALEX (2020): Alectinib (ALK+) → median PFS 34.8 months [12]
• CodeBreaK 100 (2021): Sotorasib (KRAS G12C) → ORR 41% [13]

Palliative Care:

• Temel et al. (2010): Early palliative care in metastatic NSCLC → improved QoL, mood, and survival (+2.7 months) [23]

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12. Patient and Layperson Explanation

What is Lung Cancer?

Lung cancer occurs when cells in the lung grow uncontrollably, forming a tumor. There are two main types:

1. Non-Small Cell Lung Cancer (NSCLC) – 85% of cases, grows more slowly
2. Small Cell Lung Cancer (SCLC) – 15% of cases, grows very quickly and spreads early

What Causes It?

• Smoking is the main cause (85-90% of cases). The more you smoke and the longer you smoke, the higher the risk.
• Non-smokers can get lung cancer too, especially a type called adenocarcinoma. This is more common in younger people and women.
• Other causes: Asbestos, radon gas, air pollution, family history.

What Are the Symptoms?

Many people have no symptoms early on. When symptoms occur, they may include:

• A new cough that doesn't go away or a change in a smoker's cough
• Coughing up blood (even a small amount – see a doctor urgently)
• Shortness of breath
• Chest pain
• Losing weight without trying
• Feeling very tired

Red Flags (see a doctor immediately):

• Coughing up blood
• Face/neck swelling
• Severe back pain with leg weakness
• New severe headaches or seizures

How is it Diagnosed?

1. Chest X-ray: First test, can show abnormal shadows
2. CT scan: Detailed pictures to see the tumor and if it has spread
3. Biopsy: Taking a small sample of the tumor to look at under a microscope (confirms diagnosis and guides treatment)
4. PET scan: Shows if cancer has spread to other parts of the body

What is the Treatment?

Treatment depends on the type and stage (how far it has spread):

Early Stage (Cancer Only in Lung):

• Surgery: Removing the tumor and part of the lung (best chance of cure)
• Radiotherapy: High-energy beams to kill cancer cells (if surgery not possible)

Advanced Stage (Cancer Has Spread):

• Chemotherapy: Drugs to kill cancer cells throughout the body
• Targeted Therapy: "Smart drugs" that attack specific mutations in the cancer (e.g., if you have an EGFR or ALK mutation, you can take a tablet that specifically targets this)
• Immunotherapy: Helps your own immune system fight the cancer (very effective in some people)

What is the Outlook?

It depends on:

• Stage: If caught very early (Stage I), 5-year survival is 70-90%. If it has spread (Stage IV), 5-year survival is 10-15%.
• Type: NSCLC generally has a better outlook than SCLC.
• Mutations: If your cancer has certain mutations (EGFR, ALK), targeted tablets can control it for many years.

Good News: Treatment has improved dramatically in the past 10 years with immunotherapy and targeted drugs. Some people with advanced lung cancer now live 5+ years with good quality of life.

Can Lung Cancer Be Prevented?

• Don't smoke (or quit if you do) – this is the single most important thing
• Avoid second-hand smoke
• Reduce exposure to asbestos, radon, and air pollution
• Screening: If you are 50-80 years old and a heavy smoker, you may be eligible for a yearly low-dose CT scan to catch cancer early

What Should I Do If I'm Worried?

• See your GP if you have a persistent cough (> 3 weeks), cough up blood, or unexplained weight loss
• If you smoke, ask about smoking cessation support (medications and counseling double your chance of quitting successfully)

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