Prospects for the chemoprevention of breast cancer.

Breast cancer is by far the most common type of cancer in women accounting for 20% of all new cases. It is estimated that 1 in 12 women will develop breast cancer at some time in their life. Each year in the UK, 24,500 women are newly diagnosed with breast cancer and 15,000 women die from it. The incidence rates rise from less than 10 per 100,000 women aged under 30 years to 300 per 100,000 in women aged over 85 years. The seriousness of the problem is emphasized by the fact that for women aged 35-54 years, breast cancer is the commonest single cause of all death. Both the incidence and the mortality have slightly increased in recent years, although mainly in the older age groups. There has been a slight decrease in the mortality rates for women aged 15-44 years over the last 35 years, but in all the older age groups there have been increases.