Abstract

PIP: After introducing reasons why prevention of breast cancer is needed, this proposal for preventing breast cancer with the drugs tamoxifen and gestodene is presented. Improvements in treatment of breast cancer by local surgery and adjuvant therapy can be expected to be modest at best. Screening may prevent some deaths, but is not cost effective, since the majority of cancer patients will still die. The hope of preventing breast cancer with a low fat diet is still unproven, and epidemiologic evidence so far suggests that long-term diets with 20% fat, probably taken during youth, are needed. Much more likely to be successful is formulating an oral contraceptive, and/or a post-menopausal estrogen supplement, with a steroid that prevents breast cancer. There is evidence that the new progestogen gestodene inhibits growth of breast neoplastic cells. It may work during the progression of neoplasm, displace estradiol from the cancer cell estrogen receptor, and cause breast cancer cells to secrete the negative growth modulator called TGF beta. The anti-estrogen *tamoxifen is another agent that may prove useful in preventing breast cancer. It is cytostatic for tumor cells, inhibits initiation and promotion of cancer growth, is an effective palliative treatment for existing cancer in post-menopausal women, and may even raise high-density lipoprotein cholesterol. More work needs to be done on tolerance of side effects, its biological effects on coagulation, lipid and bone metabolism, psychological and sexual consequences and its effect on cancer in pre-menopausal women. The ethics and feasibility of designing clinical trials of these drugs are discussed.