Evaluation of Ovarian Cysts in Breast Cancer Cases on Tamoxifen

Purpose: The anti-estrogen drug, tamoxifen, is one of the most important medications used in the treatment of both advanced and localized breast cancer. However, such tamoxifen use may have some risks related to the endometrium and ovaries. We followed a group of women with breast cancer on tamoxifen for the development of ovarian cysts. Methods: Based on a cross sectional study, 35 pre and post menopausal patients with breast cancer on tamoxifen were followed by pelvic exam and vaginal ultrasonography for 3 cycles of 3 month intervals; occurrence and outcome of ovarian cysts were evaluated. Results: Of the 35 tmoxifen-treated patients enrolled in this study, 21 were postmenopausal and 14 were premenopausal. Their average age was 48.1 +/- 8.7 (range: 29-65 yrs) years. The mean duration of tamoxifen therapy was 30.5 +/- 14 months (range: 12-60 months). Ovarian cysts were diagnosed in 12 (34.3%) patients, with surgery required in 6; pathological examination revealed malignancy in two cases. Conclusion: Development of ovarian cysts is a rather frequent event in women with breast cancer on tamoxifen. The majority of cysts are simple, which may resolve spontaneously or with discontinuation of tamoxifen, but malignancy needs to be ruled out.