Abstract
Results from atomic bomb survivor studies of ovarian cancer mortality and incidence in the LSS cohort, conducted at the RERF, demonstrated a dose response. The present study is on intensive pathology review of possible benign and malignant ovarian tumors. Purpose of the present report is to estimate histological-type-specific radiation risk of ovarian cancer as well as benign tumors for the period of 1950-88.Association with radiation was suggested for common epitherial carcinoma, which account for 90% of all histological types of malignant ovarian tumors. The major types of common epithelial carcinoma are serous and mucinous carcinoma. The mucinous type seems to be less radiogenic than serous type. Background ovarian cancer mortality and incidence rates are increasing in Japan. In the current study the increasing trend of background rate seems to be less steep for serous type, which is more strongly associated with radiation. This may explain, at least in part, the weaker dose response for ovarian cancer as a whole in recent years. The distribution of benign ovarian tumors by histological type is: common epitherial tumors (60%), sex-cord stromal tumors (12%), and germ cell tumors (28%). For all of these tumors, association with radiation was observed, and the relative risk for sex-cord stromal tumors in particular was greater than those of other histological types in the tentative analysis. As for common epithelial tumors, like malignant ovarian tumors, association with radiation was suggested for serous tumors, but not for mucinous tumors.
