Gastric-type mucinous carcinoma (GAS) is a novel variant of mucinous carcinoma of the uterine cervix. As shown in the original Japanese group description, in recent studies, GAS represents a more aggressive disease than the usual-type endocervical adenocarcinoma (UEA). Detailed clinicopathological features of this variant remain to be elucidated in a larger series of patients. Patients were enrolled by the Gynecologic Cancer Study Group of the Japan Clinical Oncology Group after receiving the approval of each Institutional Review Board. The study population comprised of women with stage I to II endocervical adenocarcinomas who underwent surgery between 2000 and 2009. Representative slides were evaluated by central pathological review (CPR), categorized into either GAS or UEA, and correlated with clinicopathological features and outcome. Among the 393 enrolled patients with endocervical adenocarcinoma, 328 patients met the criteria for CPR and the study eligibility criteria and were included in further analysis. A total of 95 of the 328 tumors were classified as GAS. Compared with UEA, GAS was more significantly associated with bulky mass, deep stromal invasion, lymphovascular space invasion, parametrial invasion, ovarian metastasis, positive ascitic fluid cytology, pelvic lymph node metastasis, and pathological (p) T stage but was not related to the degree of histological differentiation. Disease-free survival (P < 0.0001) and overall survival (P < 0.0001) were poorer in patients with GAS than in those with UEA. GAS showed aggressive behavior with ominous histopathological predictors as well as decreased survival. GAS is therefore considered a distinct entity that should be distinguished from UEA. UMIN Clinical Trials Registry: UMIN000007987.

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