Impact of Tamoxifen on the Ovarian Function and Pregnancy in Breast Cancer Patients

Tamoxifen is a synthetic, non-steroidal, anti-estrogenic drug that is widely used for the treatment of metastatic breast cancer patients with positive estrogen receptor proteins. Its use results a high response rate in both premenopausal and postmenopausal patients. Currently, tamoxifen is being used for prophylaxis against breast cancer in high-risk healthy women, in the treatment of benign breast disease, and in the induction of ovulation in infertile women. Breast cancer is the most common malignancy in women of reproductive age, 25% occur before menopause and 15% are diagnosed in the reproductive age group (<45 years of age). Therefore, tamoxifen is being used more frequently with premenopausal breast cancer patients; one should consider that women taking tamoxifen are potentially fertile. In breast cancer patients, ovarian cyst formation during tamoxifen has been reported in cases and in series of tamoxifen-treated breast cancer patients. The menstrual cycle in premenopausal tamoxifen-treated patients is often disturbed: irregular cycles, oli-gomenorrhea and amenorrhea occur in almost half of the patients. Even in patients with amenorrhea while taking tamoxifen, contraceptives (barriers or intrauterine devices) are necessary because pregnancies have been described. Also, according to some case reports, tamoxifen might be teratogenetic, as it can act as an anti-estrogenic agent on the developing fetus.