Adenosquamous carcinoma may have an inferior prognosis to signet ring cell carcinoma in patients with stages I and II gastric cancer

BACKGROUND: Primary gastric adenosquamous carcinoma (ASC) is an exceedingly rare histological subtype. Gastric signet ring cell carcinoma (SRC) is a unique subtype with distinct tumor biology and clinical features. The prognosis of gastric ASC vs SRC has not been well established to date. We hypothesized that further knowledge about these distinct cancers would improve the clinical management of such patients. AIM: To investigate the clinicopathological characteristics and prognosis of gastric ASC vs SRC. METHODS: A cohort of gastric cancer patients was retrospectively collected from the Surveillance, epidemiology, and end results program database. The 1:4 propensity score matching was performed among this cohort. The clinicopathological features and prognosis of gastric ASC were compared with gastric SRC by descriptive statistics. Kaplan-Meier method was utilized to calculate the median survival of the two groups of patients. Cox proportional hazard regression models were used to identify prognostic factors. RESULTS: Totally 6063 patients with gastric ASC or SRC were identified. A cohort of 465 patients was recruited to the matched population, including 370 patients with SRC and 95 patients with ASC. Gastric ASC showed an inferior prognosis to SRC after propensity score matching. In the post-matching cohort, the median cancer specific survival was 13.0 (9.7-16.3) mo in the ASC group vs 20.0 (15.7-24.3) mo in the SRC group, and the median overall survival had a similar trend (P < 0.05). ASC and higher tumor-node-metastasis stage were independently associated with a poor survival, while radiotherapy and surgery were independent protective factors for improved prognosis. Subgroup survival analysis revealed that the prognosis of ASC was inferior to SRC only in stages I and II patients. CONCLUSION: ASC may have an inferior prognosis to SRC in patients with stages I and II gastric cancer. Our study supports radiotherapy and surgery for the future management of this clinically rare entity.