Objective: To review the literature on tamoxifen side effects on the female genital tract and psychosexual function in premenopausal and postmenopausal women.
Data sources: We used the English-language literature in MEDLINE and reference lists from selected articles. Search terms included: "tamoxifen and estrogen receptor," "transcription activation," "premenopause," "postmenopause," "vaginal epithelium," "uterus," "endometrial hyperplasia," "polyps," "endometrial cancer," "sonography," "sonohysterography," "hysteroscopy," "myometrium," "myoma," "sarcoma," "endometriosis," "ovarian cysts," "hot flushes," "concentration problems," "sleep disturbance," "vaginal dryness," "sexual function," "libido," "dyspareunia," and "quality of life." No study-type restrictions were imposed.
Methods of study selection: With respect to clinical studies we included case cohort studies, observational studies; if no trials were available on a subject, case reports published in peer-reviewed journals were selected. For the discussion on endometrial surveillance of tamoxifen users, letters and editorials published in peer-reviewed journals also were used. Subjects of interest were mechanism of action of tamoxifen, tamoxifen and the vaginal epithelium, endometrium, mesenchymal tumors of the uterus, ovaries, sexual function, and vasomotor instability.
Tabulation, integration, and results: Eligible studies were analyzed to determine their usefulness in this review. Data from trials that evaluated tamoxifen side effects on specific genital tissues were combined, with special interest in differentiation of side effects in premenopausal and postmenopausal women. Weighted estimates of severity and extent of side effects were usually not possible because of lack of randomized trials. Only the risk of endometrial cancer in relation to tamoxifen treatment could be estimated.
Conclusion: The gynecologic side effects of tamoxifen are diverse and reflect the complexity of its mechanism of action, with agonistic and antagonistic effects on various tissues, depending on the ambient estradiol concentration and hence menopausal status of the patient. The most frequently reported side effect was hot flushes, and the most worrisome gynecologic side effect was a two- to three-fold increased risk of endometrial cancer in postmenopausal women. Despite its side effects, the benefits of tamoxifen in controlling breast cancer or prevention of its relapse are still without debate.