Annual vs Biennual Mammography for Breast Cancer Detection


A new study to be published in the Annals of Internal Medicine concluded that by being screened for mammogram every other year a woman’s probability of having a false positive episode is reduced by about a third-from 61% to 42% over the course of a decade. –

In the study almost 170,000 women between age 40 and 59 from seven regions of the United States and almost 4,500 women with invasive breast cancer were evaluated in relation to mammograms. Because of the added decade of testing, they found that women who started mammograms at 40 instead of 50 were more likely to have more false-positive results that lead to more treatment. The authors said “this study provides accurate estimates of the risk of a false-positive mammography and breast biopsy for women undergoing repeat mammography in community practice, and so provides important information about the potential harms of undergoing regular mammography.”
An additional report to be published in the same issue of the Annals of Internal Medicine studied almost 333.000 women between age 40 and 79 to examine the accuracy of film mammography against digital screening which is replacing the older film screening. Findings showed that overall cancer detection rates were similar for both methods but digital screening may be better for women between age 40 and 49 who are more likely to have extremely dense breasts associated with lower cancer detection. The study also found that digital mammography better detects estrogen receptor-negative tumors for women between age 40 and 49. If women start biennial screening at age 40, they will undergo 17 exams, and those who start annual screenings at age 40 will undergo 34 exams. The researchers concluded that screening every other year would likely lessen the chances of false-positive tests but “could also delay cancer diagnosis.” However, the authors found that for those diagnosed with cancer, women screened every two years were not significantly more likely to be diagnosed with late-stage cancer compared to those screened every year.

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