Summary

Colonic polyps are abnormal tissue growths that protrude from the colonic mucosa. They are extremely common, found in 30-50% of individuals over age 50 undergoing colonoscopy. Most polyps are benign, but adenomatous polyps are premalignant and follow the adenoma-carcinoma sequence to colorectal cancer. Polyp risk stratification depends on histology (adenomatous vs hyperplastic), size (>1 cm higher risk), number, and presence of villous features or high-grade dysplasia. Polypectomy during colonoscopy is both diagnostic and therapeutic. Post-polypectomy surveillance intervals are determined by polyp characteristics according to BSG/ESGE guidelines. Polyposis syndromes (FAP, Lynch syndrome, Peutz-Jeghers) require intensive surveillance and often prophylactic surgery.

Key Facts

• Prevalence: 30-50% of individuals >50 years have polyps
• Adenoma-carcinoma sequence: Adenomas can progress to cancer over 10-15 years
• Adenomatous polyps: Tubular (70%), Tubulovillous (20%), Villous (10%)
• Villous = High risk: Larger size, more dysplasia, higher malignant potential
• Hyperplastic polyps: Generally low risk (except right-sided serrated)
• Serrated polyps: Sessile serrated lesions (SSLs) are high-risk; alternative pathway to cancer
• Polypectomy: Snare polypectomy is standard; EMR/ESD for large lesions
• Surveillance: Based on BSG guidelines; high-risk = 3 years; low-risk = routine screening
• FAP: APC gene mutation; thousands of polyps; 100% cancer risk without surgery
• Lynch syndrome: MMR gene mutations; 50-80% lifetime CRC risk

Clinical Pearls

"All Adenomas Are Premalignant": Even small tubular adenomas have malignant potential. Polypectomy removes this risk. Surveillance is based on adenoma characteristics.

"Villous = Vicious": Villous adenomas have the highest malignant potential. Size, villous features, and high-grade dysplasia are key risk factors for progression.

"Right-Sided Serrated Lesions Are Dangerous": Sessile serrated lesions (formerly sessile serrated adenomas) in the right colon can be flat, difficult to see, and are precursors to serrated pathway cancers. They are often missed on colonoscopy.

"FAP = Prophylactic Colectomy": Familial adenomatous polyposis leads to 100% risk of colorectal cancer by age 40-50. Prophylactic proctocolectomy or colectomy with IRA is required.

"Lynch Syndrome = MSI-H Cancers": Hereditary non-polyposis colorectal cancer (HNPCC) is caused by MMR gene mutations. Cancers are MSI-H and respond to immunotherapy.

Why This Matters Clinically

Colonic polyps are the precursor to most colorectal cancers. Identifying and removing adenomas through colonoscopy and surveillance is the cornerstone of colorectal cancer prevention. Understanding polyp histology, risk stratification, and surveillance intervals is essential for all clinicians.[1,2]

Physical Examination

• Usually normal
• Perform DRE (digital rectal examination) — may palpate low rectal polyp
• Assess for signs of anaemia (pallor)
• Abdominal examination usually unremarkable

Polyposis Syndrome Features

Progression Risk

Surveillance Outcomes

Key Guidelines

Key Evidence

Winawer et al. (National Polyp Study)

• Colonoscopic polypectomy reduces CRC incidence by 76-90%
• Landmark evidence for polypectomy as cancer prevention
• PMID: 7848710

What are colonic polyps?

Polyps are small growths on the lining of the bowel (colon). They are very common, especially as you get older. Most polyps are harmless, but some types (called adenomas) can slowly turn into bowel cancer over many years if not removed.

How are they found?

Polyps are usually found during a colonoscopy — a camera test to look inside your bowel. Many polyps cause no symptoms.

How are they treated?

Polyps are removed during the colonoscopy using a wire loop (snare). This is painless and prevents any risk of cancer developing from that polyp.

Do I need follow-up?

It depends on the type, size, and number of polyps:

• Low-risk polyps: No extra check-ups needed; return to normal bowel screening
• Higher-risk polyps: Follow-up colonoscopy in 1-3 years to check for new polyps

What about family history?

If you have many polyps or a strong family history of bowel cancer, you may need genetic testing and more frequent colonoscopies.

High-Yield Exam Topics

Sample Viva Questions

Q1: How do you risk-stratify adenomas for surveillance?

Model Answer: According to BSG 2020 guidelines:

• Low-risk: 1-2 adenomas, all <10mm, tubular, low-grade dysplasia → Return to normal screening; no surveillance
• Intermediate-risk: 3-4 small adenomas OR at least one 10-20mm → Surveillance colonoscopy at 3 years
• High-risk: ≥5 adenomas OR at least one ≥20mm OR high-grade dysplasia → Surveillance colonoscopy at 1 year Sessile serrated lesions ≥10mm or with dysplasia are high-risk (1-year surveillance).

Q2: What is the adenoma-carcinoma sequence?

Model Answer: The adenoma-carcinoma sequence describes the stepwise genetic progression from normal colonic epithelium to adenoma to invasive carcinoma:

1. APC mutation (adenoma initiation)
2. KRAS mutation (adenoma growth)
3. SMAD4/DCC loss (late adenoma)
4. p53 mutation (transition to carcinoma) This process takes 10-15 years, which is the rationale for colonoscopic surveillance intervals. An alternative pathway is the serrated pathway (BRAF → MLH1 methylation → MSI-H cancer).

Q3: A colonoscopy shows >100 colorectal polyps. What is the diagnosis and management?

Model Answer: >100 polyps strongly suggests familial adenomatous polyposis (FAP), caused by germline APC mutation. Untreated, there is 100% risk of colorectal cancer by age 40-50. Management: Confirm with genetic testing (APC mutation). Prophylactic surgery is required — either proctocolectomy with IPAA (ileal pouch-anal anastomosis) or colectomy with ileorectal anastomosis (IRA) if rectum is relatively spared. Upper GI surveillance (duodenal adenomas). Screen first-degree relatives. Lifelong surveillance of pouch/rectum.

Common Exam Errors

Last Reviewed: 2025-12-24 | MedVellum Editorial Team

Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.