Incidence of ovarian cancer in women with prior hysterectomy in Japan

Objective. Our aim was to estimate the number of women in Japan in whom ovarian cancer could be prevented by performing prophylactic oophorectomy. Methods. Of 1289 women who were diagnosed clinically and histologically as having primary cancers of the ovary between 1986 and 1995, 53 (4.1%) had undergone hysterectomy with conservation of one or both ovaries. Clinical data and representative microscopic slides for these 53 cases were evaluated. Results. Hysterectomy had been performed at the age 45 or above in 28 of the 53 patients (53%). We estimated that performance of prophylactic oophorectomy in women who underwent a hysterectomy at age 45 or older would prevent 2.2% (4.1% x 0.53) of the cases of ovarian cancer in Japan, which is below the 3.3% estimated for women in other countries. The interval between the hysterectomy and the diagnosis of ovarian cancer ranged from 1 to 29 years (mean 9.9 years). Fourteen patients (26%) developed ovarian cancer within 5 years of the hysterectomy. The overall 3-year survival rate of these 53 patients was 65%, not significantly different from that for patients with ovarian cancer in the national study in Japan. Conclusions. Prophylactic oophorectomy for the prevention of ovarian cancer in Japanese women would appear to have a lesser impact than reported in other industrialized nations. The short interval between hysterectomy and the diagnosis of ovarian cancer observed in 26% of the patients suggested that ovarian cancer can develop within a few years of the visualization of apparently normal ovaries.