The Canadian National Breast Screening Study: a Canadian critique

The Canadian National Breast Screening Study (CNBSS) was the first study designed to determine the efficacy of screening for breast carcinoma in women 40-49 years old. Women were randomized to undergo either annual mammography and physical examination or usual care after an initial physical examination [1]. Women 50-59 years old were randomized to undergo either annual mammography and physical examination or annual physical examination only [2]. This study, published by epidemiologists on the efficacy of a radiologic examination, therefore, invites evaluation by radiologists.