- In colorectal cancer (CRC) liver metastases, submillimeter margins (R1) led to similar outcomes to ≥1 mm margins (R0) in RAS wild-type patients who responded to neoadjuvant chemotherapy (NACT).
- Outcomes were worse with R1 resection in patients with a RAS mutation or no response to NACT.
Why this matters
- The authors suggest that R1 margins are only acceptable for RAS wild-type tumors that respond to NACT.
- Retrospective analysis of 214 patients with initially resectable CRC liver metastases who underwent liver resection after receiving NACT.
- Funding: Chinese government; Chinese Society of Clinical Oncology-MERCK SERONO Oncology Research Fund.
- Among patients with response to chemotherapy (RC), OS was similar between R0 and R1 resections, but OS was lower with R1 among NACT nonresponders (5-year OS; 24.4% vs 12.8%; P=.022).
- OS was worse with R1 vs R0 resection in RAS+ NACT responders, wild-type RAS nonresponders, and RAS+ nonresponders.
- For NACT responders with wild-type RAS, there was no difference in 5-year OS between R0 and R1 (66.4% vs 65.2%; P=.884).
- Retrospective analysis.