A 50-year-old patient undergoes curative resection of a colorectal carcinoma. The surgeon notes a resection margin of 0.5 mm from the tumour (positive CRM by the ≤1 mm definition). Histopathology confirms pT3 N2 M0, R1 resection. The implication and recommended management are:

• A R1 resection has no impact on survival; no additional therapy needed
• B Immediate re-operation to achieve wider margins
• C R1 is defined as tumour at the margin only — 0.5 mm is R0
• D R1 resection carries a high risk of local and distant recurrence; adjuvant chemotherapy is indicated and re-resection should be discussed in an MDT ✓

Explanation

An R1 (microscopic positive) resection margin (≤1 mm for CRM in colorectal cancer by RCPAQAP/Royal College criteria) significantly increases local recurrence and reduces overall survival. In the MDT setting, adjuvant chemotherapy (CAPOX or FOLFOX for 3–6 months) is indicated for pN2 disease regardless of margin. Re-resection of the pelvis is high-risk and discussed only if feasible and margins are resectable; pelvic re-irradiation may be considered if not previously irradiated.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.