Intraoperative revision of a positive proximal resection margin is associated with improved survival in patients undergoing resection for gastroesophageal junction and proximal third gastric adenocarcinoma.

[BACKGROUND] Positive proximal resection margins after resection for gastroesophageal junction (GEJ) and proximal third of the stomach portend poor survival. Although associated with unfavorable tumor biology rather than technical insufficiency, the benefit of re-resecting intraoperatively encountered positive proximal margin, especially in locally advanced gastric cancers (GCs), is uncertain.

[METHODS] A total of 388 consecutive patients with proximal third gastric and Siewert type II and III GEJ adenocarcinomas who underwent radical resection between 2010 and 2022 were analyzed for R1 resection rates and the effect of margin conversion from R1 to R0 on long-term survival.

[RESULTS] Of note, 91 patients (23%) had an initial positive proximal resection margin, of which 69 patients (75%) were converted to R0 after frozen section analysis. Moreover, 22 patients (5.6%) had persistent R1 margins on final pathology. The R0 resection group had a 3-year overall survival (OS) of 70%, which fared best, whereas the R1-to-R0 resection group had a 3-year OS of 55%. However, patients with R1 resection fared poorly, with a 3-year OS of 36%. The median disease-free survival estimates for the R0, R1-to-R0, and R1 groups were 42, 28, and 18 months, respectively. Among the node-positive patients, we found a significant OS benefit for margin revision in N1 disease (P =.036) but not in N2 or N3 disease (P =.51).

[CONCLUSION] A positive resection margin is an independent poor prognostic factor, regardless of the tumor stage. Conversion of an intraoperatively encountered R1 margin to an R0 resection status is associated with improved survival and should be performed even in locally advanced GCs, especially in N0 and N1 diseases.