On this page
Study tools
Write your answer
Saved on this device. No marking — you are the marker.
Stem A (elective left-sided CRC)
A 62-year-old man presents with 3 months of altered bowel habit (alternating constipation and diarrhoea), fresh rectal bleeding mixed with stool, and 6 kg weight loss. Father had colorectal cancer at age 58. Examination: pale; palpable left iliac fossa mass; DRE normal. Hb 9.2 g/dL (MCV 68), iron-deficiency pattern.
Stem B (emergency obstruction — for part d)
Separately, a 70-year-old with a known sigmoid stricture presents with absolute constipation, distension, and peritonism. CT: obstructing sigmoid tumour, free fluid, no free gas. He is tachycardic and hypotensive after fluids.
Questions
a) Stem A diagnosis, side-based presentation pattern, and three initial investigations. (3 marks)
Left-sided colorectal carcinoma (altered habit + bleeding + LIF mass + IDA + family history).
Patterns: right = insidious anaemia/weight loss/occult blood; left = obstruction/altered habit/annular lesion; rectum = bleeding, tenesmus, DRE mass.
Investigations: (1) colonoscopy + biopsy (and exclude synchronous lesions); (2) CT chest/abdomen/pelvis staging; (3) baseline CEA (monitoring, not diagnosis). Complete colonoscopy or CT colonography of residual colon if obstructing lesion prevents full exam.
b) Biopsy adenocarcinoma; CT: T3 tumour, 2 regional nodes, no mets. Stage, operation, oncological principles, adjuvant therapy with regimen names. (4 marks)
Stage III (node-positive, M0).
Left hemicolectomy (or sigmoid colectomy as appropriate) with high vascular ligation (IMA territory), ≥12 lymph nodes, adequate margins, primary anastomosis if safe.
Adjuvant FOLFOX (oxaliplatin 85 mg/m² + leucovorin + 5-FU) or CAPOX (capecitabine + oxaliplatin) for 3–6 months (MOSAIC established oxaliplatin benefit in stage III). MSI-H stage II may not need 5-FU.
c) Family history — syndrome, diagnostic criteria, relative surveillance. (4 marks)
Consider Lynch syndrome (HNPCC) (MMR defect).
Amsterdam II: ≥3 relatives with Lynch-spectrum cancer; one first-degree of the other two; ≥2 generations; ≥1 diagnosed <50; FAP excluded.
Also use Bethesda criteria to select tumours for MSI/IHC testing.
Surveillance for proven/at-risk: colonoscopy from ~25–30 (or 10 years before youngest case) every 1–2 years; counsel gynaecological risk (endometrial/ovarian) in women.
d) Stem B — resuscitation and definitive emergency operation with rationale. (4 marks)
ABC, oxygen, large-bore IV access, crystalloid, NG tube, catheter, bloods/lactate/crossmatch, broad-spectrum IV antibiotics if peritonism/sepsis (e.g. piperacillin-tazobactam 4.5 g IV TDS or co-amoxiclav + metronidazole).
Unstable obstructed left colon ± contamination → Hartmann’s procedure (resection + end colostomy + rectal stump) — avoids anastomosis in unprepared/unstable bowel.
Stable selected malignant left obstruction may use SEMS as bridge to elective resection in specialist centres (perforation risk). Right-sided obstruction often resection + primary anastomosis if fit.
Additional teaching points
Rectal cancer: TME standard; neoadjuvant SCRT or long-course CRT for stage II–III; AR vs APER by height/sphincter.
Screening: USPSTF from age 45 — colonoscopy 10-yearly or annual FIT.
FAP: APC, hundreds of polyps, prophylactic colectomy by ~20–25 years.