Ovarian overstimulation and cystic formation in premenopausal tamoxifen exposure: Comparison between tamoxifen-treated and nontreated breast cancer patients

Aim. Tamoxifen is the antihormonal treatment of choice for premenopausal br east cancer patients with advanced breast disease. Its premenopausal admini stration has been shown to induce supraphysiological 17 beta-estradiol seru m levels and to be associated with the presence of persistent, bilateral fu nctional ovarian cysts. However, these abnormalities have not yet been comp ared to controls. In this study we evaluated the possibility that the above hormonal and/or ovarian abnormalities are more frequent among premenopausa l breast cancer patients treated with tamoxifen than among similar nontreat ed patients, and thus they may be attributed to tamoxifen effect. Methods. We evaluated serum hormone levels of 17 beta-estradiol, follicular -stimulating hormone, lutenizing hormone, and progesterone, the presence of ovarian cysts, and various demographic and clinical characteristics in 20 premenopausal breast cancer patients treated with tamoxifen (study group) a nd compared them to those observed in 12 similar nontreated patients (contr ol group). Results. Ovarian cysts were found in 80% of the study patients and only in 8.3% of the control patients (P = 0.001). The incidence of oligomenorrhea w as nearly significantly higher in the study than in the control group (50 a nd 16.7%, respectively; P = 0.0651). Various serum hormone levels tested we re not found to be significantly different between the two groups, except f or 17 beta-estradiol serum levels as detected on days 14 and 21 of the mens trual cycle, which were significantly higher among the study than in the co ntrol patients. (Day 14 serum estradiol: 757.7 +/- 372.0 pg/mL versus 206.5 +/- 275.0 pg/mL, P = 0.0012. Day 21 serum estradiol: 300.0 +/- 134.5 pg/mL versus 96.5 +/- 71.5 pg/mL, P = 0.0008.) Conclusions. Tamoxifen treatment increases the incidence of ovarian cysts a nd the significantly higher 17 beta-estradiol serum levels in premenopausal breast cancer patients. (C) 1999 Academic Press.