Screening Mammography Outcomes

Risk of Breast Cancer and Mortality by Comorbidity Score and Age

Joshua Demb; Linn Abraham; Diana L. Miglioretti; Brian L. Sprague; Ellen S. O'Meara; Shailesh Advani; Louise M. Henderson; Tracy Onega; Diana S. M. Buist; John T. Schousboe; Louise C. Walter; Karla Kerlikowske; Dejana Braithwaite

Disclosures

J Natl Cancer Inst. 2020;112(6):599-606. 

In This Article

Abstract and Introduction

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.

Introduction

Because of the heterogeneity in health status and life expectancy among older women, defined as age 65 years and older, the margin of benefit from screening mammography varies widely.[1–3] Evidence exists that women with multiple consequential comorbidities are in fact more likely to undergo screening mammography than their counterparts without comorbidity—an indication of greater access to care—even though they may not experience a net benefit from screening.[4,5] In a systematic review of observational studies and decision analyses, we have found that healthy older women with favorable life expectancies may indeed benefit from continued screening mammography unlike those with major comorbidity.[2]

Given the long natural history of breast cancer in older women and increased risk of non–breast cancer death with aging, there may be a point when older women may not live long enough to benefit from screening mammography.[1,2,6–8] Moreover, because rates of slow-growing tumors increase with age, older women with limited life expectancies may experience less benefit from screening and a greater likelihood of harms from overdiagnosis and overtreatment,[1,9–11] including a potential inability to tolerate or complete treatment regimens.[12,13] Perhaps reflecting this uncertainty, professional guidelines vary in their recommendations about upper age limits for screening cessation. For example, the American Cancer Society (ACS) recommends stopping screening when life expectancy is less than 10 years,[14] whereas the US Preventive Services Task Force (USPSTF) states that there is insufficient evidence to recommend for or against screening women ages 75 years and older;[15] most European screening programs stop inviting women for screening between ages 69 and 74 years.[16]

Overall, there is a paucity of empirical evidence on long-term risk of breast cancer juxtaposed with death from breast cancer and other non–breast cancer-related causes according to comorbidity and age among older women undergoing screening mammography.[1,2] As a critical step toward informing clinical decisions in this area, our objective in this study was to determine the 10-year cumulative incidence of breast cancer vs death from causes other than breast cancer (hereafter referred to as other-cause death) according to comorbidity and age in the Medicare-linked Breast Cancer Surveillance Consortium (BCSC), a population-based cohort of women undergoing breast imaging in US clinical practice settings.

The institutional review board at Georgetown University approved this study.

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