Improving survival of stage II‐III primary gastric signet ring cell carcinoma by adjuvant chemoradiotherapy

BACKGROUND: There is no consistent evidence about the appropriate treatment strategies for gastric signet ring cell carcinoma (GSRC) to improve prognosis. We conducted a population‐based study to examine the effects of combined modality therapies on survival outcomes using the Surveillance, Epidemiology, and End Results (SEER) data. METHODS: Analyses included stage II‐III primary GSRC patients who were diagnosed between 2006 and 2016. Therapies were categorized as gastrectomy group, adjuvant chemotherapy (CT) group, neoadjuvant radiotherapy (RT) group, and adjuvant chemoradiotherapy (CRT) group. Survival analyses were conducted by Kaplan‐Meier method and Cox proportional hazards models and subgrouped by gender, tumor site, stage at diagnosis, and number of lymph nodes removed. RESULTS: Of the 1717 cases of stage II‐III primary GSRC, the mean (SD) age was 59.6 (13.3) years, and over a half were male (52.8%). A total of 39.9% patients received adjuvant CRT and the 5‐year overall survival (OS) rate was 34.6%. The median OS of patients treated with adjuvant CRT was significantly longer than that of the gastrectomy group (33 months vs 24 months, aHR = 0.71, 95% CI: 0.59, 0.84). Although the crude model showed a significant association between adjuvant CT and total survival (cHR = 0.81, 95% CI: 0.68, 0.96), the effect measure turned null in the multivariable and sub‐group analysis. We did not find the significant effect of neoadjuvant RT. CONCLUSIONS: In this study, GSRC patients with stage II‐III experienced improved overall survival after receiving adjuvant CRT, which provides several treatment implications. More clinical trials will be needed to verify the conclusion derived from this study.