"After an average 13-year follow-up, our research shows no mortality benefit from mammography screening in this age group in spite of the fact that mammography diagnosed far more cancers," says Dr. Anthony Miller, a professor emeritus in the Faculty of Medicine's public health sciences department and lead author of the study in the Sept. 3 issue of the Annals of Internal Medicine. "This is the only trial to date specifically designed to evaluate breast screening among women aged 40 to 49."

The study involved 50,000 volunteers in their 40s, recruited from 1980 to 1985, who were not pregnant, had no previous breast cancer diagnosis, and had not had a mammogram in the previous 12 months. Participating at 15 screening centres across Canada, the women were randomly assigned to one of two groups - 25,214 received four or five annual mammography screenings and breast physical examinations and 25,216 women received a single breast physical examination followed by usual care from their personal physician. Both groups were instructed on breast self-examination.

In the study, physicians provided breast physical examinations in three centres in Quebec and nurses in the 12 remaining centres. The physicians and nurses also taught and evaluated breast self-examination while conducting their own examination. Two-view mammography was done on dedicated mammography units.

Cancer detection was higher with mammography than in the group screened by physical examination alone - 87 versus 58 cases at the first screening exam. After 13 years of follow-up, 592 women in the mammogram group were diagnosed with invasive breast cancer compared to 552 in the usual care group. As of 1996, 105 wome
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Contact: Janet Wong
jf.wong@utoronto.ca
416-978-5949
University of Toronto
2-Sep-2002