Abstract
OBJECTIVE: To assess the impact of the NHS breast screening programme on the incidence of and mortality from breast cancer. DESIGN: Comparison of age specific incidence and mortality before and after the introduction of screening in the late 1980s. SETTING: England and Wales. SUBJECTS: Women aged over 30 years. RESULTS: In 1992 the age standardised incidence of breast cancer was 40% higher than in 1979. After the introduction of screening in 1988 recorded incidence rates rose steeply in the screened age group (50-64 year olds) but not in others. In 1992 the rates levelled off at about 25% higher than in 1987. Total mortality from breast cancer has increased steadily since the 1950s; the rates increased earlier in the younger age groups. By the mid-1980s rates had begun to fall in the younger age groups; but total mortality was still among the highest in the world. Age standardised mortality in the 55-69 age group changed little during the first three years of screening but then fell steeply and in 1994 was 12% lower than in 1987. CONCLUSIONS: Since the introduction of screening there have been pronounced increases in recorded incidence in the screened age group. Cancer registries have an essential role in assessing screening programmes and cancer services. The steep decrease in mortality in 55-69 year olds which began three years after screening started is unlikely to be due to screening. The widespread adoption of treatment with tamoxifen during this period may be important. With the reduction in mortality already observed and the expected additional benefits from screening, the Health of the Nation target should be achieved.