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Mammograms less accurate in breast cancer survivors

February 23, 2011

Mammograms are more likely to miss tumors in women who have had breast cancer before than in those without a history of the disease, according to a study published in the Journal of the American Medical Association.   For the study, the accuracy and outcomes from 58,870 screening mammograms in 19,078 women with a history of early-stage (in situ or stage I-II invasive) breast cancer were compared to the accuracy and outcomes from 58,870 matched (breast density, age group, mammography year, and registry) screening mammograms in 55,315 women with no history of breast cancer.

Within a year of screening, 655 tumors were found in women with a history of breast cancer, compared to 342 in women with no history.  Though women with a history of breast cancer were receiving more frequent mammograms, 35% of new tumors were not detected by mammography in these women, compared with 24% for women with no history.  Women with a history of breast cancer were also more likely to have false positive results and be told that the mammogram might be showing a cancer, when in fact there was no cancer.