{"entity":{"id":"r0-r1-margin-pancreatic","kind":"term","name":"R0 and R1 margins in pancreatic cancer: the 1 mm rule and standardised specimen reporting","aka":["1 mm rule","R1 within 1 mm","R1 direct","Royal College of Pathologists pancreatic margin","Leeds protocol","Axial slicing of pancreatoduodenectomy specimens","Circumferential resection margin of the pancreas","Posterior margin","Superior mesenteric vein groove margin","Superior mesenteric artery margin"],"tldr":"After a pancreatic cancer is removed, the pathologist checks whether cancer reaches the cut edges of the specimen. In the UK, cancer within one millimetre of an edge counts as an incomplete (R1) resection even if it does not touch it. Reported this way most operations are R1, because the tumour creeps along nerves behind the gland; cancer touching the edge carries a worse outlook.","summary":"The general glossary term explains R0, R1 and R2; pancreatic cancer needs its own entry because the definition changed the numbers. The Royal College of Pathologists' pancreatoduodenectomy dataset defines R1 as microscopic tumour within 1 mm of a resection margin, and when a standardised protocol of multicolour inking of the margins, axial slicing and extensive sampling was introduced in Leeds, the R1 rate for pancreatic head cancer was 85 percent (22 of 26), involvement was often multifocal and most often posterior, and margin status correlated with survival (Verbeke 2006). In Heidelberg the R1 rate rose from 14 percent without a protocol to 76 percent with one, the medial (superior mesenteric vessel) margin being involved in 68 percent and the posterior in 47 percent, leading the authors to conclude that tumour growth pattern and thoroughness of examination, not surgical technique, determine R1 rates (Esposito 2008). In Liverpool 79 percent of 163 resections were R1 and 45 percent of those were equivocal (within 1 mm but not touching); their survival did not differ from unequivocal R1, supporting the 1 mm rule (Campbell 2009). Applying the strict definition to 561 pancreatoduodenectomies, 20.0 percent were R0 (1 mm or more), 21.9 percent R1 within 1 mm and 58.1 percent R1 direct, and margin status remained an independent determinant of survival even with adjuvant therapy in 85.9 percent, the authors calling for an international consensus because R0 and R1 rates are not comparable between series that use different definitions (Strobel 2017). In the ESPAC-3 adjuvant trial, 505 of 1,151 patients (43.9 percent) were R1; median survival was 24.9 months for R0 (more than 1 mm), 25.4 months for R1 within 1 mm, and direct margin involvement carried significantly worse overall and recurrence-free survival and more local recurrence (Ghaneh 2019). The margin that matters most is the medial or superior mesenteric artery margin, which is why neoadjuvant therapy (which shrinks the tumour away from the vessels) and vascular resection are judged partly by the R0 rate they achieve; the DIPLOMA trial used R0 of 1 mm or more as its primary endpoint (Korrel 2023). The R status is recorded alongside the TNM stage and node count and does not change the recommendation to give adjuvant chemotherapy.","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Resection_margin","links":[{"label":"Verbeke, Br J Surg 2006: redefining the R1 resection in pancreatic cancer","url":"https://doi.org/10.1002/bjs.5397"},{"label":"Esposito, Ann Surg Oncol 2008: most pancreatic cancer resections are R1 resections","url":"https://doi.org/10.1245/s10434-008-9839-8"},{"label":"Campbell, Histopathology 2009: classification of R1 resections, tumour within 1 mm of a margin","url":"https://doi.org/10.1111/j.1365-2559.2009.03376.x"},{"label":"Strobel, Ann Surg 2017: pancreatic cancer surgery, the new R-status counts (561 patients)","url":"https://doi.org/10.1097/sla.0000000000001731"},{"label":"Ghaneh, Ann Surg 2019: positive resection margins, survival and recurrence in ESPAC-3 (1,151 patients)","url":"https://doi.org/10.1097/sla.0000000000002557"},{"label":"Korrel, Lancet Reg Health Eur 2023: DIPLOMA, minimally invasive versus open distal pancreatectomy for resectable pancreatic cancer","url":"https://doi.org/10.1016/j.lanepe.2023.100673"}],"tags":["gi","pancreatic"],"related":[],"cancers":["pancreatic","resectable-pdac","borderline-resectable-pdac","ipmn-associated-carcinoma"],"sections":[],"technologies":["histopathology-ihc"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["resection-margins","whipple","distal-pancreatectomy","vascular-resection-pancreatic","neoadjuvant-versus-upfront-surgery-pancreatic","tnm-staging"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Pathology"},"route":"/terms/r0-r1-margin-pancreatic/","neighbours":{"cancer":[{"id":"borderline-resectable-pdac","kind":"cancer","name":"Borderline resectable pancreatic ductal adenocarcinoma","route":"/cancers/borderline-resectable-pdac/"},{"id":"ipmn-associated-carcinoma","kind":"cancer","name":"Invasive carcinoma arising in an intraductal papillary mucinous neoplasm (IPMN-associated carcinoma)","route":"/cancers/ipmn-associated-carcinoma/"},{"id":"pancreatic","kind":"cancer","name":"Pancreatic ductal adenocarcinoma","route":"/cancers/pancreatic/"},{"id":"resectable-pdac","kind":"cancer","name":"Resectable pancreatic ductal adenocarcinoma","route":"/cancers/resectable-pdac/"}],"technology":[{"id":"histopathology-ihc","kind":"technology","name":"Histopathology & immunohistochemistry","route":"/technologies/histopathology-ihc/"}],"term":[{"id":"distal-pancreatectomy","kind":"term","name":"Distal pancreatectomy (removal of the body and tail of the pancreas, usually with the spleen)","route":"/terms/distal-pancreatectomy/"},{"id":"neoadjuvant-versus-upfront-surgery-pancreatic","kind":"term","name":"Neoadjuvant therapy versus surgery first for resectable and borderline resectable pancreatic cancer","route":"/terms/neoadjuvant-versus-upfront-surgery-pancreatic/"},{"id":"resection-margins","kind":"term","name":"Resection margins (R0 / R1 / R2)","route":"/terms/resection-margins/"},{"id":"tnm-staging","kind":"term","name":"TNM staging","route":"/terms/tnm-staging/"},{"id":"vascular-resection-pancreatic","kind":"term","name":"Vascular resection in pancreatic cancer surgery (portal and superior mesenteric vein resection; arterial resection)","route":"/terms/vascular-resection-pancreatic/"},{"id":"whipple","kind":"term","name":"Whipple procedure (pancreaticoduodenectomy)","route":"/terms/whipple/"}]}}