Re-resection of Microscopically Positive Margins Found on Intraoperative Frozen Section Analysis Does Not Result in a Survival Benefit in Patients Undergoing Surgery and Intraoperative Radiation Therapy for Locally Recurrent Rectal Cancer

BACKGROUND: Intraoperative frozen-section analysis provides real-time margin resection status that can guide intraoperative decisions made by the surgeon and radiation oncologist. For patients with locally recurrent rectal cancer undergoing surgery and intraoperative radiation therapy, intraoperative re-resection of positive margins to achieve negative margins is common practice. OBJECTIVE: This study aimed to assess whether re-resection of positive margins found on intraoperative frozen-section analysis improves oncologic outcomes. DESIGN: This is a retrospective cohort study. SETTINGS: This study was an analysis of a prospectively maintained multicenter database. PATIENTS: All patients who underwent surgical resection of locally recurrent rectal cancer with intraoperative radiation therapy between 2000 and 2015 were included and followed for 5 years. Three groups were compared: initial R0 resection, initial R1 converted to R0 after re-resection, and initial R1 that remained R1 after re-resection. Grossly positive margin resections (R2) were excluded. MAIN OUTCOME MEASURES: The primary outcome measures were 5-year overall survival, recurrence-free survival, and local re-recurrence. RESULTS: A total of 267 patients were analyzed (initial R0 resection, n = 94; initial R1 converted to R0 after re-resection, n = 95; initial R1 that remained R1 after re-resection, n = 78). Overall survival was 4.4 years for initial R0 resection, 2.7 years for initial R1 converted to R0 after re-resection, and 2.9 years for initial R1 that remained R1 after re-resection (p = 0.01). Recurrence-free survival was 3.0 years for initial R0 resection and 1.8 years for both initial R1 converted to R0 after re-resection and initial R1 that remained R1 after re-resection (p ≤ 0.01). Overall survival did not differ for patients with R1 and re-resection R1 or R0 (p = 0.62). Recurrence-free survival and freedom from local re-recurrence did not differ between groups. LIMITATIONS: This study was limited by the heterogeneous patient population restricted to those receiving intraoperative radiation therapy. CONCLUSIONS: Re-resection of microscopically positive margins to obtain R0 status does not appear to provide a significant survival advantage or prevent local re-recurrence in patients undergoing surgery and intraoperative radiation therapy for locally recurrent rectal cancer. See Video Abstract at http://links.lww.com/DCR/B886.