Methodologic issues in the chemoprevention of breast cancer

Interest in preventing breast cancer has centered on two possible interventions--restriction of dietary fat intake and prophylaxis with tamoxifen. Uncertainty about the most important age at which fat intake should be reduced, severe problems in achieving compliance, and uncertainty about dietary fat intake as a risk factor make a trial of dietary fat restriction logistically very difficult, extremely expensive, and a very long-term enterprise with uncertain outcome. A trial of tamoxifen prophylaxis is not without its logistic difficulties and the outcome is by no means certain, but the prospects of getting a clear answer within 10 years are much better, and this would appear to be the most attractive option for preventing breast cancer at present.