Utility of the proximal margin frozen section for resection of gastric adenocarcinoma: A 7-institution study of the U.S. gastric cancer collaborative.

Abstract

103 Background: The proximal gastric margin dictates the extent of resection for gastric adenocarcinoma (GAC). The value of achieving negative margins by additional gastric resection after a positive proximal margin frozen section (FS) is unknown. Methods: The US Gastric Cancer Collaborative includes all patients who had resection of GAC at 7 institutions by oncologic surgeons from 2000-2012. Intraoperative proximal margin FS data were classified as R0 or R1 based on final permanent section (PS); positive distal margins were excluded. Primary aim was to evaluate the impact on local recurrence (LR) of converting a positive proximal margin FS to an R0 final margin by additional resection. Secondary endpoints were recurrence-free (RFS) and overall survival (OS). Results: Of 860 pts, 520 had a proximal margin FS; 67 were positive. Of these 67, 48 were converted to R0 on PS by additional resection. R0 proximal margin was achieved in 447 pts (86%), R1 in 25 (5%), and R1 converted to R0 in 48 (9%). Median FU was 44 mos. Although LR was decreased in the converted R1 to R0 group compared to the R1 group (10% vs 32%, p=0.01), when accounting for other pathologic variables on multivariate (MV) analysis, R1 to R0 conversion was not associated with decreased LR. Median RFS was similar between the R1 to R0 and R1 cohort (37 vs 31 mos; p=0.6) compared to 110 mos for the R0 group. Median OS was similar between the R1 to R0 conversion and R1 groups (36 vs 26 mos; p=0.14) compared to 50 mos for the R0 group. On MV analysis, increasing T-stage and positive lymph nodes were associated with worse OS; R1 to R0 conversion of the proximal margin was not associated with improved OS (p=0.5; Table). Conclusions: Conversion of a positive intraoperative proximal margin frozen section during gastric cancer resection does not decrease local recurrence or improve recurrence-free or overall survival. This may guide decisions regarding the extent of resection. [Table: see text]