Colorectal Carcinoma — Viva

Q1: Presentation patterns (2 min)

• Right: iron-deficiency anaemia, occult blood, mass, late
• Left: altered habit, obstructive symptoms, bleeding mixed with stool
• Rectum: fresh bleeding, tenesmus, DRE mandatory
• Adult male/postmenopausal IDA → colonoscopy

Q2: Adenoma–carcinoma and molecular paths (2 min)

• APC → KRAS → TP53 over 10–15 years (screening window)
• MSI-H/dMMR: Lynch or sporadic MLH1 methylation — right-sided, mucinous, immunotherapy-responsive metastatic
• FAP: APC germline, carpeting polyps, near-100% lifetime risk

Q3: Staging work-up (2 min)

• Colonoscopy + biopsy; CT CAP; baseline CEA
• Rectal: MRI pelvis for T/N and CRM; consider TRUS; full colon assessment
• PET not routine for initial colon staging

Q4: Colon operations and principles (3 min)

• Right/extended right/left/sigmoid/subtotal by site
• High vascular tie, en-bloc, ≥12 nodes, 5 cm margins (colon)
• Laparoscopic equivalent oncologically in experienced hands
• Stage III adjuvant FOLFOX/CAPOX (MOSAIC)

Q5: Rectal cancer specifics (3 min)

• TME reduces local recurrence from ~30% to <10%
• Upper/mid: anterior resection ± defunctioning stoma
• Low/sphincter involved: APER, permanent colostomy
• Neoadjuvant SCRT (25 Gy/5#) or long-course CRT 45–50.4 Gy + fluoropyrimidine

Q6: Emergency obstruction/perforation (2 min)

• Resuscitate; antibiotics if septic
• Unstable left obstruction: Hartmann’s
• SEMS bridge in selected stable left malignant obstruction
• Perforation: sepsis source control, resection, often stoma

Q7: Hereditary and special populations (2 min)

• Lynch: Amsterdam II, colonoscopy from 25–30 q1–2y; extracolonic screening
• FAP: colectomy by 20–25; duodenal surveillance
• UC: surveillance from ~8 years; dysplasia → colectomy discussion
• Pregnancy/elderly: individualise imaging and emergency vs bridge strategies

Q8: Follow-up pearls (1 min)

• CEA for monitoring recurrence, not diagnosis
• Rising CEA → CT ± colonoscopy
• Lifestyle: smoking, red/processed meat, obesity as modifiable risks