The R classification of surgical resection margins is used in oncological surgery. A patient undergoes pancreatic cancer resection and the histopathology shows tumour cells within 1 mm of the posterior retroperitoneal margin (closest margin). What R-classification should be assigned according to the Leeds Pathology Protocol?
- A R0 — curative resection
- B R1 (direct) — tumour cells present AT the inked margin
- C R1 — tumour cells within 1 mm of the margin using the 1 mm clearance rule ✓
- D R2 — macroscopic residual disease
Correct answer: C. R1 — tumour cells within 1 mm of the margin using the 1 mm clearance rule
Explanation
The Leeds protocol (Verbeke et al.) and European guidelines for pancreatic cancer apply a 1 mm clearance rule: R1 is assigned when tumour cells are within 1 mm of the resection margin (regardless of whether they are at the inked edge). In contrast, the traditional protocol defines R1 only when tumour cells are at the inked margin (0 mm), making R0 >0 mm clearance. With the 1 mm rule, R1 rates in pancreatic cancer rise from ~20% to ~80%, more accurately reflecting the poor prognosis. This is clinically important for treatment decisions.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.