Adjuvant Therapy Improves Survival for T2N0 Gastric Cancer Patients with Sub-optimal Lymphadenectomy.

BACKGROUND: The benefit of adjuvant therapy following resection of early stage, node-negative gastric adenocarcinoma following a margin negative (R0) resection is unclear.

METHODS: The National Cancer Data Base was used to identify patients with a T2N0 gastric adenocarcinoma (tumor invasion into the muscularis propria) who underwent R0 resection. Patients treated with neoadjuvant therapy and those for whom lymph node count was unavailable were excluded from the analysis. Kaplan-Meier and Cox regression were used to evaluate differences in and predictors of overall survival.

RESULTS: A total of 1687 patients underwent R0 resection for T2N0 gastric adenocarcinoma between 2003-2011. Adjuvant chemotherapy treatment was administered to 7.1 and 14.1 % received adjuvant chemoradiation; 65.4 % had <15 lymph nodes examined. Multivariate Cox regression identified higher Charlson score, <15 lymph nodes examined, higher tumor grade, and tumor location in the cardia as factors associated with significantly decreased overall survival. With a median follow-up of 36 months, the 5-year overall survival was 71 % for patients with ≥15 lymph nodes examined and 53 % for those with <15 lymph nodes (p < 0.001). In patients who had <15 lymph nodes examined, there was an overall survival benefit for adjuvant chemoradiation (hazard ratio 0.71, p = 0.043). In patients with ≥15 lymph nodes examined, no survival benefit for adjuvant therapy was identified (p > 0.74).

CONCLUSIONS: Adequate lymph node dissection and pathologic staging is critical in directing optimal treatment of patients with early gastric cancer. Understaging as a result of suboptimal lymphadenectomy may explain the perceived benefit of adjuvant chemoradiation after an R0 resection for T2N0 gastric cancer.