The canadian national breast screening study: why it deserves support.

The National Breast Screening Study was designed to show whether screening with mammography and physical examination of the breasts reduces mortality from breast cancer in volunteers aged 40-49 and to determine the incremental effect of mammography over and above any effect of physical examination in women aged 50-59.In spite of the high incidence of breast cancer in these two age groups, both physicians and the public have shown reluctance to support the trial. This reluctance appears to be based on lack of understanding of the nature of screening tests and on concern about the hazards of radiation. The design and justification for the study is discussed and placed in the context of the principles of screening. The risks of radiation are minimal; in the study the cumulative exposure will be less than one RAD after five annual mammograms, and new evidence shows that women in their forties are not as susceptible to risks from radiation to the breasts.