Prevention of breast cancer

Breast cancer is the most common cancer in women in the United Kingdom and despite advances in treatment, metastatic disease remains incurable and many women die from the disease. There is extensive biologic and clinical evidence implicating estrogenic stimulation in the development and progression of breast cancer. The success of tamoxifen in adjuvant breast cancer trials in delaying the recurrence of disease and preventing second primary breast cancers and, in postmenopausal women, conferring a survival benefit, has led to increasing interest in the use of tamoxifen as a chemopreventive agent against breast cancer. It remains to be seen whether tamoxifen will act as a true preventive agent or whether it will merely delay the appearance of breast cancer, in which case the use of the drug may alter the natural history of the disease in women who have been exposed to tamoxifen. The optimal duration of drug intervention, the appropriate target population for chemoprevention, and the cost-benefit ratio of tamoxifen prevention are all issues that must be formally addressed in carefully controlled trials. Some data concerning duration and side effects are already available from epidemiologic studies and long-term clinical follow-up of patients exposed to tamoxifen.