Risk factors and the prevention of breast cancer with tamoxifen.

Overview

Oestrogen is intimately involved in the growth and development of breast cancer. Tamoxifen, a non-steroidal anti-oestrogen, not only is an effective adjuvant therapy for node positive and node negative disease, but also has several attractive pharmacological features that have enhanced interest in testing it as a preventive drug for breast cancer in high risk women. Tamoxifen is known to prevent contralateral breast cancer, but it also has significant oestrogenicity for reducing circulating cholesterol and preventing bone loss in the lumbar spine of postmenopausal women. Several clinical trials have been initiated around the world; however, there has been increasing concern about the safety of tamoxifen. Nevertheless, current reports indicate that there is little risk of developing endometrial and liver cancer, although further clinical studies must be planned. Concerns about retinal and thromboembolic problems remain anecdotal, and again additional research is essential. The prevention trials with tamoxifen are necessary to establish the worth and feasibility of a pharmacological intervention. If tamoxifen is found to be of value to prevent breast cancer in a broad population, then the future ability to predict breast cancer through molecular markers will provide the physician for the first time with a therapeutic option to treat the targeted patient.