[Evaluation of early detection of breast cancer in Great Britain (author's transl)].

A large-scale trial of methods of early detection of breast cancer has been started in Great Britain. This non-randomized trial aims to compare breast cancer mortality over several years among women aged 45-64 years who have been offered various services for early detection of breast cancer. A quantitative assessment of benefits (lives saved) and costs (unnecessary surgery, radiation hazard, and use of health service resources) will be made. A total population of over 250,000 women living in eight districts is being studied in the trial. In two districts the women are invited for annual screening by clinical examination and mammography; in two other districts they are invited to teaching sessions to learn breast self-examination. The remaining four districts, with a population of 120,000 women, serve as a comparison and have no extra services beyond conventional diagnostic facilities. A register of all breast histology among these women has been set up, and, for those who have breast cancer, details of diagnosis, treatment and annual follow-up are recorded. All changes to the population are noted, and the cause of all deaths recorded. Factors influencing acceptance of early detection programmes, and the sensitivity and specificity of different screening methods are being studied. Mortality rates from breast cancer in the three types of population (screening, self-examination and comparison groups) will be the main index of effectiveness, but other questions relative to evaluation of screening, such as lead-time natural history of pre-invasive neoplasia, and identification of high-risk women, will also be assessed.