Borderline ovarian tumors in Finland: epidemiology and familial occurrence.

A total of 1,197 borderline ovarian tumors were reported to the Finish Cancer Registry in 1973-1992. The mean age of the patients was 52 years, while the mean age of the 7,060 patients with an invasive epithelial ovarian carcinoma reported in the same time period was 62 years. The incidence of borderline ovarian tumors did not increase with age after patients became 35 years old and older. The overall age-adjusted incidence of borderline ovarian tumors was 1.8 per 100,000 women-years. Familial cancer occurrence during 1967-1992 was studied among relatives of 144 index patients diagnosed in 1980-1982. No borderline ovarian tumors were detected in the relatives, and only one of the 446 female first-degree relatives had an epithelial ovarian cancer. The expected number (borderline and invasive combined) was 1.9. The mothers of the index patients had an increased risk for pancreatic cancer (standardized incidence ratio 4.9, 95% confidence interval 1.0-14.3) and for cancer of the uterine cervix (standardized incidence ratio 7.8, 95% confidence interval 1.6-22.8). No significant increase in cancer risk was observed for fathers, brothers, or sisters of the patients with borderline ovarian tumors.