The results of a mammographic screening study suggest that some invasive breast cancers may spontaneously regress over time.
These findings “provide new insight on what is arguably the major harm associated with mammographic screening, namely, the detection and treatment of cancers that would otherwise regress,” Dr. H. Gilbert Welch, from the Department of Veteran Affairs Medical Center, White River Junction, Vermont, and colleagues state.
The study involved 119,472 women, from 50 to 64 years of age, who underwent three rounds of mammography screening from 1996 to 2001 as part of the Norwegian Breast Cancer Screening Program.
The cancer rates in this group were compared with those in 109,784 control women who would have been screened had the program been in place in 1992.
Women in the control group were invited to undergo a one-time screen at the conclusion of their observation period, the authors explain.
As anticipated, the 4-year cumulative incidence of invasive breast cancer in the screened group was higher than in the control group before screening: 1268 vs. 810 cases per 100,000 population.
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