Multiple primary cancers of the breast, endometrium and ovary.

The association between cancers of the breast, endometrium and ovary is reviewed, using mainly population-based data from the cancer registries in Denmark and Connecticut, U.S.A. Breast cancer patients had an approximately three-fold increased risk of developing a cancer in the contralateral breast. The risk of breast cancer was also elevated following cancers of the corpus uteri and ovary, with relative risk (RR) estimates of about 1.5 from 1 to 4 years after the diagnosis of the first primary cancer. An increased risk of cancer of the corpus uteri subsequent to breast cancer was found in Connecticut, but not in Denmark. After an ovarian cancer, the risk of cancer of the corpus uteri was also elevated (RR = 1.6-2.3). An increased risk of ovarian cancer was observed subsequent to breast cancer (RR = 1.3-1.7), whereas the ovarian cancer risk decreased with time since the diagnosis of a cancer of the corpus uteri, probably reflecting treatment involving oophorectomy.