Objective: Endometrial cancer and breast cancer are two common malignancies found in women. As a result of estrogen dependency, an association is thought to exist between these entities. This study was undertaken to determine if the endometrial carcinomas, which develop in women with a history of breast cancer, were more likely to be of the endometrioid or the serous histology, which is generally considered non-estrogen-dependent.
Methods: A retrospective chart review was conducted for the years 1984-2001. All women who were diagnosed at our institution with endometrial carcinoma were identified. The women who also had a prior history of breast cancer were identified and comprise the cohort for this study. Information regarding age at diagnosis, tumor stage, histologic subtype, and tamoxifen exposure were recorded and analyzed.
Results: About 1166 women were diagnosed with endometrial cancer during the study period, of whom 54 (4.6%) had a pre-existing diagnosis of breast cancer. Of the 54 women in this study, 41 had tumors of the endometrioid histology and 13 had a tumor of the serous subtype. There was no difference with regards to median age at the time of diagnosis or years of tamoxifen exposure. Women with breast cancer were more likely to develop uterine serous carcinoma (USC) as compared to one of endometrioid histology (OR 2.6; 95% CI 1.29-5.23).
Conclusions: Women with breast cancer who subsequently developed endometrial cancer exhibited a 2.6-fold increased risk of developing a USC as compared to an endometrioid carcinoma. These findings suggest that there may be an underlying genetic predisposition linking breast cancer and USC.