Ovarian epithelial tumors of borderline malignancy in Japan.

Seventy-one cases of ovarian epithelial tumor of borderline malignancy have been surveyed from a clinicopathologic viewpoint. The majority of the borderline tumors (73.2%) were of the mucinous type, versus only 16.9% of the serous type. The other types--endometrioid (2.8%), Brenner (1.4%), and mixed type (5.6%)--were much rarer. Patients with mucinous tumors were significantly younger (mean age 42.6) than those with serous tumors (mean age 57.5) (P less than 0.01). Of patients with mucinous tumors, 64.2% were of reproductive age (15-45 years), compared with 17% of patients with serous tumors. Some 78.8% of mucinous and 83.3% of serous borderline tumors were FIGO stage I. Serous tumors were more frequently bilateral (66.7%) than mucinous tumors (9.8%). In mucinous borderline tumors, the extent of tumor spread at the first laparotomy had an intimate relationship to the prognosis, but in serous borderline tumors, it was insignificant. The survival rate of patients with mucinous borderline tumors was 69.3% at 5 years and 62.4% at 10 years (Kaplan-Meier method). Most patients with pseudomyxoma peritonei classified as borderline at the time of discovery died within 5 years of the operation. The prognosis of the serous type was extremely favorable. Criteria for borderline tumors of various cell types and differences in the clinicopathologic data of ovarian borderline tumors between Japan and other countries were discussed.