Purpose: The anti- estrogen drug, tamoxifen, is one of the most important medications used in the treatmentof both advanced and localized breast cancer. However, such tamoxifen use may have some risks related to theendometrium and ovaries.We followed a group of women with breast cancer on tamoxifen for the developmentof ovarian cysts. Methods: Based on a cross sectional study, 35 pre and post menopausal patients with breastcancer 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 enrolledin 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). Ovariancysts were diagnosed in 12 (34.3%) patients, with surgery required in 6; pathological examination revealedmalignancy in two cases. Conclusion: Development of ovarian cysts is a rather frequent event in women withbreast cancer on tamoxifen. The majority of cysts are simple, which may resolve spontaneously or withdiscontinuation of tamoxifen, but malignancy needs to be ruled out.
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