The R classification of surgical margins uses R0, R1, and R2. In the context of pancreatic cancer resection, the ISGPS (International Study Group of Pancreatic Surgery) definition of R1 margin is:

• A Any tumour cell at the inked margin (0 mm)
• B Gross visible tumour at the margin intraoperatively
• C Tumour cells within 1 mm of the resection margin ✓
• D Positive lymph nodes adjacent to resection margin

Explanation

The ISGPS and UK Royal College of Pathologists definitions define R1 for pancreatic resection as tumour cells within 1 mm of the resection margin (not necessarily at the ink). This 1 mm clearance definition is more stringent than the 0 mm (at ink) definition and results in R1 rates of 50–80% in pancreatic cancer series, explaining high recurrence rates. R2 denotes macroscopic residual disease.

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

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Written and medically reviewed by the StethoPrep medical team.