Primary gastric choriocarcinoma: two case reports and a pooled analysis of 53 cases.

Primary gastric choriocarcinoma (PGC) is a rare tumor. In total, approximately 140 cases of PGC have been reported in the international medical literature. However, the clinical behavior, tumor characteristics, and prognostic parameters of PGC have not been clearly described. We conducted a pooled analysis to clarify the tumor characteristics and prognostic parameters in 53 patients with PGCs, including 2 patients treated at our hospital. The following variables were examined as potential prognostic factors: (1) sex, (2) age, (3) depth of invasion, (4) size, (5) histology, (6) nodal metastasis, (7) distant lymph node metastasis, (8) synchronous liver metastasis, (9) residual tumor, and (10) chemotherapy (not given or given). Univariate and multivariate analyses showed that the presence of residual tumor and synchronous liver metastasis and the absence of chemotherapy were significantly associated with an increased hazard rate (HR) of short overall survival (OS). Pooled analysis, including the two patients with PGC treated at our facility, demonstrated that the presence of a curative operation and chemotherapy, and the absence of synchronous liver metastasis were the strongest indicators of a favorable clinical course in patients with PGC.