A 68-year-old with rectal cancer at 6 cm from the anal verge undergoes anterior resection. During histopathological reporting, the surgeon's concern is the circumferential resection margin (CRM). A positive CRM is defined as tumor within what distance from the surgical margin?
- A Within 5 mm
- B Within 1 mm ✓
- C Within 2 mm
- D At the margin or direct contact with the margin
Correct answer: B. Within 1 mm
Explanation
A positive circumferential resection margin (CRM+) in rectal cancer surgery is defined as tumor cells within 1 mm of the mesorectal fascia margin on histopathological examination. CRM positivity is a major independent predictor of local recurrence and reduced survival. The 1 mm threshold was established through landmark work by Quirke et al. and is incorporated into the Royal College of Pathologists reporting guidelines. A 2 mm threshold is sometimes used as a cautionary zone, but the formal definition of CRM positivity is ≤1 mm.
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.