Tamoxifen and incidence of gynecologic tumors - Tips from Other Journals

Date: Feb 1, 1994

Tamoxifen is widely used in the treatment of estrogen-receptor-positive breast cancer. In hypoestrogenic women, it has a weak estrogen effect. The effectiveness of tamoxifen plus its low reported incidence of side effects have led to consideration of other wide-scale use, particularly in prophylaxis of breast cancer and treatment of benign gynecologic diseases. However, several reports of endometrial and other gynecologic tumors occurring in women during tamoxifen treatment have been published. Seoud and colleagues reviewed the literature and the records of patients attending a university medical center to establish any association between tamoxifen therapy and an increased risk of gynecologic malignancy.

Between 1985 and 1992, symptomatic gynecologic tumors developed in six postmenopausal patients taking tamoxifen, 20 mg per day, for breast cancer. Three patients had endometrial adenocarcinoma, one had endometrial polyps with glandular hyperplasia, one had fallopian tube carcinoma, and one had mixed mullerian sarcoma. None of these patients had radiation treatment, and all but two had used tamoxifen for more than two years.

The world literature now reports 70 cases of gynecologic malignancies in women treated with tamoxifen. Many of these reports are anecdotal, and the data from large series of patients are difficult to interpret. Some studies have found a statistically significant increased risk, particularly in women who also received irradiation in the pelvic area or who took tamoxifen for longer than two years. Conversely, other studies have reported no cases of endometrial adenocarcinoma.

All of the study results have been obscured by the small numbers of cancer occurrences, different approaches to monitoring patients and screening for the development of malignancies, and varying treatment protocols, particularly dosages of tamoxifen and use of pelvic irradiation.

Tamoxifen is a safe and reliable treatment for breast cancer. hi view of the concerns about a possible link to gynecologic malignancies, particularly endometrial adenocarcinoma, the authors recommend close monitoring of patients and prompt investigation of gynecologic symptoms. (Obstetrics and Gynecology, August 1993, vol. 82, p. 165.)

EDITOR'S NOTE: Family physicians increasingly care for survivors of breast cancer, many of whom are treated with tamoxifen. It is not currently clear whether these reported cases of gynecologic malignancy are tamoxifen-induced, related to factors that induced the breast adenocarcinoma, or being discovered due to more intensive monitoring of tamoxifen-treated patients. The literature describes only those cases that have been published, and both the unpublished cases and the total number of tamoxifen-treated women need to be considered in order to put the reports into perspective. These reports could either be an early warning of a significant aspect of care for breast cancer survivors or a "false alarm" triggered by rare events. In either case, the need for comprehensive, long-term monitoring of women with breast cancer is emphasized.--Anne D. Walling, M.D.

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