Benefits and Harms of Screening Mammography Frequency by Age and Comorbidity Score

Background: There is uncertainty about the appropriate use of screening mammography in older women. We compared the benefits and harms of screening mammography frequency according to age and comorbidity scores.

Methods: We conducted analyses within a prospective cohort study of four mammography registries in the Breast Cancer Surveillance Consortium that had mammography data linked to Medicare claims information. Participants included 137,949 women aged 66–89 years without breast cancer and 2,993 women with breast cancer. We estimated odds of advanced (IIb, III, IV) stage, large tumor size (>20 millimeters), and estrogen receptor (ER) negative tumors and cumulative probability of false-positive mammography after 10 years of screening by mammography frequency, age and comorbidity score as determined by the Charlson Comorbidity Index.

Results: Mammography biennially vs. annually for women aged 66–89 years does not increase risk of tumors with unfavorable characteristics regardless of women's comorbidity score. Cumulative probability of a false-positive result for annual and biennial screening of women aged 66–89 years with a comorbidity score of ≥1 was 48 (46.1, 49.9) and 29 (28.1, 29.9) respectively. False-positives were more common among annual screeners than among those screened biennially irrespective of women's comorbidity score.

Conclusion: Mammography annually vs. biennially does not have added benefit for women aged 66–89 years, even among those in good overall health as reflected by the lack of comorbidity. Risk of false-positive mammography is much higher with annual mammography.