Radiotherapy Improves the Prognosis in Signet Ring Cell Carcinoma and Non-Signet Ring Cell Gastric Adenocarcinoma Patients: A SEER Database Analysis

Objective: To investigate the effect of radiotherapy on prognosis in gastric signet ring cell carcinoma (SRCC) and gastric non-signet ring cell adenocarcinoma (NSRCC) patients. Methods: A total of 23,971 patients diagnosed with gastric cancer were collected from 2004 to 2013 by SEER database, including 17,679 NSRCC patients and 6,292 SRCC patients. Patients were divided to two groups and compared according to whether radical gastrectomy was performed on them. After clinic pathological characteristics of the two groups were balanced by the propensity score matching (PSM) method, survival rates of the two groups were then compared. Results: The Over Survival (OS) and Cancer-Specific Survival (CSS) time of SRCC and NSRCC patients in the radiotherapy groupwere significantly better than those in the non-radiotherapy group. But the clinical and pathological characteristics (gender, age, pathological differentiation degree, T stage, N stage, and metastasis) of the two groups were significantly unbalanced (p<0.001). After 1:1 PSM matching, it was found that radiotherapy had no significant effect on OS and CSS time of NSRCC patients, but radiotherapy could significantly improve OS and CSS time of SRCC patients. Conclusion: SRCC patients are more sensitive to radiotherapy than NSRCC patients. Although the prognosis of SRCC is far less than that of NSRCC patients, the treatment strategy of surgical resection of primary lesions combined with radiotherapy should be recommend for SRCC patients, and whether radiotherapy benefits NSRCC patients still needs to be further studied.