Second cancer following cancer of the female genital system in Denmark, 1943-80.

Between 1943 and 1980, approximately 53,000 women in Denmark survived 2 or more months after initial diagnosis of cancers of the cervix uteri, corpus uteri, ovaries, fallopian tubes, and ligaments. No significant excess of new cancers was observed following cancers of the cervix and corpus uteri. However, after second cancers of both the cervix and corpus uteri were eliminated from the analysis (because it was likely they were surgically removed or not recorded due to conservative coding practices), 6 and 4% excess risks of borderline significance were found among women with cancer of the cervix and uterus, respectively. A significant 25% excess of all second primary cancers was observed following cancer of the ovary (relative risk = 1.25; 95% CI = 1.14-1.37). Significant excesses of colon and breast cancers followed cancers of the ovary and corpus uteri. Subsequent to cervical cancer, the risk of cancers of the lung, esophagus, bladder, and kidney occurred significantly above expectation. These associations may be explained by common risk factors related to reproduction and possibly diet for cancers of the breast, colon, ovary, and corpus uteri; and to cigarette smoking for cancers of the lung, esophagus, bladder, and cervix uteri. The significant deficit of breast cancer after cervical cancer could be due to different patterns of risk factor (i.e., reproductive and socioeconomic variables) and loss of functioning ovaries as a part of the treatment for cervical cancer. Each of the female genital sites showed significant excesses of second bladder cancers, and the risk increased significantly with time, which indicate a relation to radiotherapy. The pattern of risk of leukemia observed following cancer of the ovary was also compatible with effects of treatment, especially chemotherapy.