The circumferential resection margin (CRM) status reported in rectal cancer histopathology is defined as positive when tumour is within what distance from the cut circumferential margin, and what is its clinical significance?

• A Within 1 mm; independently predicts local recurrence and reduced survival ✓
• B Within 5 mm; predicts systemic metastases only
• C At the inked margin; irrelevant if proximal margin is clear
• D Within 2 mm; indicates need for immediate re-excision

Explanation

The CRM is considered positive (CRM+) when tumour cells, including extramural vascular invasion or tumour deposits, are within 1 mm of the surgically cut mesorectal surface. A positive CRM is the strongest independent predictor of local recurrence (up to 78% vs ~3%) and significantly reduces 5-year survival. It guides decisions on adjuvant therapy. Re-excision is rarely feasible; adjuvant radiotherapy may be considered.

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.