A 62-year-old man presents with a 3-month history of alternating constipation and diarrhoea, with blood-stained stools and weight loss of 4 kg. On examination, a palpable mass is felt in the left lower abdomen. Colonoscopy reveals a stenosing lesion at the rectosigmoid junction with biopsy confirming adenocarcinoma. CT staging shows tumour confined to the bowel wall with no distant metastases. The patient is fit for surgery. Which of the following is the most appropriate surgical approach for this patient?

Explanation

## Surgical Management of Rectosigmoid Cancer ### Clinical Context This patient has a stenosing rectosigmoid adenocarcinoma (tumour at the junction of rectum and sigmoid colon) without distant metastases. The tumour is resectable and the patient is fit for curative surgery. ### Rationale for Low Anterior Resection (LAR) **Key Point:** Low anterior resection with total mesorectal excision (TME) is the gold standard for tumours of the rectosigmoid region that are resectable and allow adequate distal margin (≥2 cm). **High-Yield:** The rectosigmoid junction is defined as the junction between the sigmoid colon and rectum, typically 15–20 cm from the anal verge. Tumours in this region can usually be managed by LAR with primary anastomosis, provided: - Adequate distal clearance (≥2 cm) is achievable - The patient's sphincter function is preserved - No contraindications to anastomosis exist **Clinical Pearl:** Total mesorectal excision (TME) is mandatory for all rectal cancers to reduce local recurrence rates from ~40% (without TME) to <10% (with TME). This involves removing the rectum and surrounding mesorectum en bloc. ### Comparison of Surgical Options | Procedure | Indication | Outcome | |-----------|-----------|----------| | **Low Anterior Resection (LAR)** | Rectosigmoid/upper rectal cancers with adequate distal margin | Curative; preserves continence; primary anastomosis | | **Hartmann's Procedure** | Acute obstruction, perforation, or very low rectal cancers; temporary measure | Creates colostomy; requires reversal surgery later | | **Abdominoperineal Resection (APR)** | Very low rectal cancers (<5 cm from anal verge) with sphincter involvement | Curative but permanent colostomy; significant morbidity | | **Palliative Bypass** | Unresectable tumours or poor performance status | No tumour removal; symptom relief only | **Key Point:** Hartmann's procedure is NOT first-line for elective resectable cancer in a fit patient — it is reserved for emergency situations (perforation, acute obstruction) or as a temporary measure when anastomosis is unsafe. ### Why LAR is Optimal Here 1. Tumour is resectable and confined to bowel wall (no T4 invasion) 2. Patient is fit for major surgery 3. Rectosigmoid location allows ≥2 cm distal margin 4. Curative intent with sphincter preservation 5. TME reduces local recurrence **Mnemonic: RECTOSIGMOID SURGERY — LAR is the STAR** - **L**ow **A**nterior **R**esection = standard for rectosigmoid - **S**phincters **T**ypically **A**voided (preserved) - **R**emove mesorectum (TME) [cite:Sabiston Textbook of Surgery Ch 51]