Impact of external-beam radiation therapy on outcomes among patients with resected gastric cancer: A multi-institutional analysis

Background. Use of perioperative chemotherapy (CTx) alone versus chemoradiation therapy (cXRT) in the treatment of resectable gastric cancer remains varied. We sought to define the utilization and effect of CTx alone versus cXRT on patients having undergone curative-intent resection for gastric cancer.Methods. Using the multi-institutional US Gastric Cancer Collaborative database, we identified 505 gastric cancer patients between 2000 and 2012 who received perioperative therapy in addition to curative-intent resection. The impact of perioperative therapy on survival was analyzed by the use of propensity-score matching of clinicopathologic factors among patients who received CTx alone versus cXRT.Results. Median patient age was 62 years, and most patients were male (58.2%). Most patients had a T3 (38.7%) or T4 (36.8%) lesion and lymph node metastasis (73.4%). A total of 211 (42.8%) patients received perioperative CTx alone, whereas the remaining 294 (58.2%) patients received cXRT. Factors associated with receipt of cXRT were younger age (odds ratio, 1.93) and lymph node metastasis (odds ratio, 4.02; both P < 0.05). At a median follow-up of 28 months, the median overall survival (OS) was 33.4 months, and the 5-year OS was 36.7%. Factors associated with worse overall survival included large tumor size [hazard ratio (HR), 1.83], T3 (HR 2.96) or T4 (HR 4.02) tumors, and lymph node metastasis (HR 1.57; all P < 0.05). In contrast, receipt of cXRT was associated with improved long-term OS (CTx alone, 20.9 months; cXRT, 46.7 months; HR 0.51; P < 0.001). Conclusions. cXRT was utilized in 58% of patients undergoing curative-intent resection for gastric cancer. With propensity score-matched analysis, cXRT was an independent factor associated with improved recurrence-free survival and OS.