# Resection margins (R0 / R1 / R2)

Source: https://onco.cc/terms/resection-margins/  
OnCo record `resection-margins` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Whether the edge of the removed tissue is free of cancer. R0 means clear under the microscope, R1 means microscopic cancer at the edge, R2 means visible tumour left behind. R0 is what 'complete resection' means.

## Summary

Margin status is the strongest surgeon-controlled predictor of local recurrence and, in several cancers, of survival. An R1 margin often means further surgery, radiotherapy or, in pancreatic cancer, simply a worse prognosis; R2 resections are palliative. The required width varies: 'no ink on tumour' suffices for invasive breast cancer, 1 mm for the circumferential margin in rectal cancer, 1-2 cm for melanoma. Neoadjuvant therapy is often justified by its ability to raise the R0 rate, as with daraxonrasib in pancreatic cancer.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: margins; margin; surgical margins; negative margins; positive margins; margin-negative; margin-positive; clear margins; R0; R0 resection; R1 resection; R2 resection; microscopic residual disease; margin status; circumferential resection margin; CRM; positive margin; resection margin

## Notes

- Pancreatic cancer uses a 1 mm rule: tumour within 1 mm of a margin is R1 (Royal College of Pathologists), which makes 76 to 85 percent of standardised head resections R1; the pancreatic glossary term carries the series and the ESPAC-3 survival by margin (Ghaneh 2019).

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Resection_margin
- Wikipedia: https://en.wikipedia.org/wiki/Resection_margin
- Campbell, Histopathology 2009: classification of R1 resections, tumour within 1 mm of a margin: https://doi.org/10.1111/j.1365-2559.2009.03376.x
- Ghaneh, Ann Surg 2019: positive resection margins, survival and recurrence in ESPAC-3 (1,151 patients): https://doi.org/10.1097/sla.0000000000002557

## Connected records

- terms: [Adrenalectomy](https://onco.cc/terms/adrenalectomy/), [Breast conservation or mastectomy](https://onco.cc/terms/breast-conserving-surgery-versus-mastectomy/), [Circumferential resection margin (rectal cancer)](https://onco.cc/terms/circumferential-resection-margin/), [Cystic duct margin](https://onco.cc/terms/cystic-duct-margin/), [Cytoreductive surgery](https://onco.cc/terms/cytoreductive-surgery/), [Distal pancreatectomy (removal of the body and tail of the pancreas, usually with the spleen)](https://onco.cc/terms/distal-pancreatectomy/), [Extranodal extension (ENE)](https://onco.cc/terms/extranodal-extension/), [Extraprostatic extension and seminal vesicle invasion](https://onco.cc/terms/extraprostatic-extension/), [GIST risk stratification (mitotic count, size, site; Miettinen and modified NIH criteria)](https://onco.cc/terms/gist-risk-stratification/), [Hepatectomy (liver resection)](https://onco.cc/terms/hepatectomy/), [Limb-salvage surgery](https://onco.cc/terms/limb-salvage-term/), [Lumpectomy (breast-conserving surgery)](https://onco.cc/terms/lumpectomy/), [Lymphovascular invasion (LVI)](https://onco.cc/terms/lymphovascular-invasion/), [Mohs surgery](https://onco.cc/terms/mohs-surgery/), [Perineural invasion (PNI)](https://onco.cc/terms/perineural-invasion/), [R0 and R1 margins in pancreatic cancer: the 1 mm rule and standardised specimen reporting](https://onco.cc/terms/r0-r1-margin-pancreatic/), [Resectable, borderline resectable and unresectable](https://onco.cc/terms/resectability/), [The growth pattern on a basal cell carcinoma report: nodular, superficial, infiltrative, basosquamous](https://onco.cc/terms/bcc-growth-pattern/), [The margin in skin cancer surgery](https://onco.cc/terms/surgical-margins-keratinocyte-cancer/), [Tumour bed boost](https://onco.cc/terms/tumour-bed-boost/), [Tumour size on a breast report, and why it differs from the scan](https://onco.cc/terms/breast-tumour-size-on-the-report/), [What makes a skin cancer high risk: the UK feature lists](https://onco.cc/terms/skin-cancer-high-risk-features/), [Whipple procedure (pancreaticoduodenectomy)](https://onco.cc/terms/whipple/), [Whole-mount pathology](https://onco.cc/terms/whole-mount-pathology/), [Wide local excision](https://onco.cc/terms/wide-local-excision/)
- cancers: [Adenosquamous carcinoma of the pancreas](https://onco.cc/cancers/pancreatic-adenosquamous-carcinoma/), [Basal cell carcinoma](https://onco.cc/cancers/basal-cell-carcinoma/), [Borderline resectable pancreatic ductal adenocarcinoma](https://onco.cc/cancers/borderline-resectable-pdac/), [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [Cutaneous squamous cell carcinoma](https://onco.cc/cancers/cutaneous-scc/), [Invasive carcinoma arising in an intraductal papillary mucinous neoplasm (IPMN-associated carcinoma)](https://onco.cc/cancers/ipmn-associated-carcinoma/), [Locally advanced unresectable pancreatic ductal adenocarcinoma](https://onco.cc/cancers/locally-advanced-pdac/), [Mucinous cystic neoplasm of the pancreas with associated invasive carcinoma (MCN-associated carcinoma)](https://onco.cc/cancers/mcn-associated-carcinoma/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/), [Pancreatoblastoma](https://onco.cc/cancers/pancreatoblastoma/), [Resectable pancreatic ductal adenocarcinoma](https://onco.cc/cancers/resectable-pdac/), [Skin cancer (all types)](https://onco.cc/cancers/skin-cancer/), [Undifferentiated carcinoma of the pancreas with osteoclast-like giant cells](https://onco.cc/cancers/pancreatic-undifferentiated-carcinoma-ogc/)
- fronts: [Diagnostics & Biomarkers](https://onco.cc/fronts/diagnostics/), [Surgery & Interventional](https://onco.cc/fronts/surgery/)
- key papers: [Preoperative Chemoradiotherapy Versus Immediate Surgery for Resectable and Borderline Resectable Pancreatic Cancer: Results of the Dutch Randomized Phase III PREOPANC Trial](https://onco.cc/key-papers/paper-preopanc-preoperative-chemoradiotherapy-jco-2020/)
- roadmaps: [Pancreatic cancer roadmap: from Whipple's operation to gemcitabine, FOLFIRINOX, adjuvant chemotherapy, PARP inhibition, KRAS inhibition, vaccines and the surveillance question](https://onco.cc/roadmaps/pancreatic-roadmap/)
- ideas: [Chemotherapy before surgery for every resectable pancreatic cancer, settled by the two perioperative trials rather than assumed](https://onco.cc/ideas/idea-pdac-neoadjuvant-chemotherapy-for-all-resectable-disease/)
- trials: [Alliance A021501](https://onco.cc/trials/alliance-a021501/), [CONKO-007](https://onco.cc/trials/conko-007/), [EORTC 22881-10882 (boost against no boost)](https://onco.cc/trials/eortc-22881-boost/), [Mohs surgery against ordinary excision for facial basal cell carcinoma (Maastricht trial)](https://onco.cc/trials/mohs-versus-excision-facial-bcc/), [NSABP B-06](https://onco.cc/trials/nsabp-b06/)

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