A different view on what is known about breast screening and the canadian national breast screening study

Although many who are interested in breast screening will be familiar with the criticisms that have been launched at the Canadian National Breast Screening Study (NBSS),',' fewer will be aware of the frequently flawed nature of these criticisms. Whatever the truth proves to be, it is unquestionable that the controversy about the efficacy of screening women 40-49 years of age not only is alive and well, but also does not serve the best interests of women of any age. It is a public health catastrophe that young women fear the hazards of breast cancer more than the hazards of smoking, that they greatly overestimate their risk of getting breast cancer, and that older women who can benefit from screening are not receiving it, In this issue, Kopans et al. offer yet another article in support of screening for breast cancer in women younger than the age of 50. In contrast, others such as the U.S. Preventive Services Task Force, recommend otherwise. The credibility of the evidence used to support either opinion is often influenced by what the reader wants to believe. It is important to recognize that everyone, regardless of how he or she evaluates existing evidence, wants to achieve reduction in the morbidity and mortality associated with breast cancer. No one is immune to the human suffering associated with the dis- ease. The publication of NBSS results in 1992 caused considerable controver~y.~-~ At a 7-year follow-up of women aged 40-49 years,' 25,214 who had received annual mammography and clinical examination of the breast displayed a statistically insignificant excess of