Screening Mammography Outcomes: Risk of Breast Cancer and Mortality by Comorbidity Score and Age

Abstract Background Potential benefits of screening mammography among women ages 75 years and older remain unclear. Methods We evaluated 10-year cumulative incidence of breast cancer and death from breast cancer and other causes by Charlson Comorbidity Index (CCI) and age in the Medicare-linked Breast Cancer Surveillance Consortium (1999–2010) cohort of 222 088 women with no less than 1 screening mammogram between ages 66 and 94 years. Results During median follow-up of 107 months, 7583 were diagnosed with invasive breast cancer and 1742 with ductal carcinoma in situ; 471 died from breast cancer and 42 229 from other causes. The 10-year cumulative incidence of invasive breast cancer did not change with increasing CCI but decreased slightly with age: ages 66–74 years (CCI0 = 4.0% [95% CI = 3.9% to 4.2%] vs CCI ≥ 2 = 3.9% [95% CI = 3.5% to 4.3%]); ages 75–84 years (CCI0 = 3.7% [95% CI = 3.5% to 3.9%] vs CCI ≥ 2 = 3.4% [95% CI = 2.9% to 3.9%]); and ages 85–94 years (CCI0 = 2.7% [95% CI = 2.3% to 3.1%] vs CCI ≥ 2 = 2.1% [95% CI = 1.3% to 3.0%]). The 10-year cumulative incidence of other-cause death increased with increasing CCI and age: ages 66–74 years (CCI0 = 10.4% [95% CI = 10.3 to 10.7%] vs CCI ≥ 2 = 43.4% [95% CI = 42.2% to 44.4%]), ages 75–84 years (CCI0 = 29.8% [95% CI = 29.3% to 30.2%] vs CCI ≥ 2 = 61.7% [95% CI = 60.2% to 63.3%]), and ages 85 to 94 years (CCI0 = 60.3% [95% CI = 59.1% to 61.5%] vs CCI ≥ 2 = 84.8% [95% CI = 82.5% to 86.9%]). The 10-year cumulative incidence of breast cancer death was small and did not vary by age: ages 66–74 years = 0.2% (95% CI = 0.2% to 0.3%), ages 75–84 years = 0.29% (95% CI = 0.25% to 0.34%), and ages 85 to 94 years = 0.3% (95% CI = 0.2% to 0.4%). Conclusions Cumulative incidence of other-cause death was many times higher than breast cancer incidence and death, depending on comorbidity and age. Hence, older women with increased comorbidity may experience diminished benefit from continued screening.