Trial of early detection of breast cancer: description of method.

A large-scale trial has been started in the United Kingdom with the aim of evaluating the effectiveness of different methods for the early detection of breast cancer. Two populations, each of 25,000 women aged 45-64 are invited for annual screening by mammography and/or clinical examination. Two further populations, one of 25,000 and one of 40,000 women in the same age range, are invited for education sessions in breast self-examination, and 4 control populations, totalling 120,000 women, are offered no additional services beyond conventional diagnostic facilities. All breast histology, both benign and malignant, in all women in the study is recorded, as are the findings, management and follow-up of all breast cancers. Changes in the populations, and deaths from all causes, are also recorded. This is essentially a non-randomized trial, though in one of the screening centres, where an education programme about breast cancer is provided for the whole population, only women registered with certain randomly selected general practices are invited to be screened. The principal means of evaluation will be the comparison of the mortality rates from breast cancer in each of the study populations. Costs, in terms of use of health resources, unnecessary surgery and radiation hazard, will be assessed. Additional aspects of the trial include studies of women's attitudes to early detection, and of the aetiology of breast cancer.