FEASABILITY OF CHEMOPREVENTION OF BREAST- CANCER BY TAMOXIFEN

Breast cancer is a frequent disease especially in the Western world wi th an incidence that increases by 1% each year. Distressingly, even no wadays, 40% of patients with breast cancer will die of their disease. Postoperative adjuvant therapy mid detection of non-palpable cancers b y mass screening of women have improved patients survival but have not impinged upon tire steady increase in incidence. Treatment before rad iological detection could improve the chances of survival and even pre vent the full-blown expression of the disease. The probability that a woman will develop breast cancer during her life-time is high but not evenly distributed. Knowledge of predisposing factors can help to iden tify those women subject to greater risk than the general population. The most important known risk factors are age, family history, factors related to ob-gyn antecedents, lifestyle, benign hyperplastic breast disease with or without atypia. These various risks, are often associa ted and cumulative. A woman who has already had breast cancer has a 3 to 5 times greater probability of developing cancer of the contralater al breast than the average woman. The second breast is therefore at ri sk in the same way as are the women with predisposing factors. Many cl inical studies have demonstrated the benefits of postoperative adjuvan t tamoxifen (TAM) in improving the disease-free interval and survival of patients. All analysis of the site of relapse has interestingly bro ught to light a marked decrease in the percentage of cancers of the co ntralateral breast. In order to establish whether TAM could prevent or delay the onset of breast cancer, it is necessary to design clinical trials that will specifically confirm or refute this hypothesis. This means randomization of high-risk women without detectable signs of ill ness into groups receiving either TAM or placebo. Is this ethically ac ceptable? The answer to this question rests heavily ol all objective e valuation of the unwanted and beneficial side-effects of TAM in order to weigh lip all pros and cons before initiating a trial.