The benefits and ethics of screening for breast cancer

Abstract

Background Breast cancer is probably the disease feared most by women in the UK. Not only is the disease itself seen as fatal, but its treatment also poses tremendous psychological threats. The incidence of breast cancer has been steadily rising in the UK. In 1960, 20,000 women in England and Wales had a new diagnosis of breast cancer, at a rate of 60 per 100,000. By 1984 that number had risen to 24,000) Over the same period deaths from this disease have risen comparably from 12,000 to 15,000 per year. Indeed breast cancer mortality is one of the few things in which we lead the world. The UK rate is five times higher than that experienced by Japan, and almost twice as high as that experienced by most other countries of Western Europe} Whilst highlighting the seriousness of the disease in Britain these wide variations in mortality suggest that the disease is amenable to control if only we could understand the underlying basis of these differences. Sadly, despite much effort on epidemiological studies, we still know little of the cause of breast cancer or how to prevent it. Comparison of five-year survival rates in breast cancer show a relatively optimistic improvement. Of those diagnosed in 1960 60% were alive five years later, a figure that increased to 70% for those diagnosed in 1980. However, five-year survival rates are influenced by the point in time at which the disease is diagnosed. Simply diagnosing the tumour at an earlier time in its developmental course logically tends to longer survival following diagnosis (the 'lead time' effect). Therefore earlier diagnosis per se automatically produces better five-year survival rates. It is uncertain to what extent this earlier diagnosis is responsible for the increase in survival rates. Comparison with the overall mortality rate would suggest that much of the improvement in survival rates may be accounted for by lead-time. It remains true that around two-thirds of women who develop breast cancer will eventually die from the condition. Breast cancer therefore remains a substantial public health concern and the UK national breast screening programme can be seen within the political imperative of doing something about that concern, and being seen to be doing something.