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Invited Commentary
Oncology
August 26, 2021

Breast Density, Risk of Breast Cancer, and Screening Mammography in Women 75 Years and Older

Author Affiliations
  • 1Section of Breast Radiology, Department of Radiology, ChristianaCare Helen F. Graham Cancer Center and Research Institute, Newark, Delaware
JAMA Netw Open. 2021;4(8):e2124385. doi:10.1001/jamanetworkopen.2021.24385

To my knowledge, few publications and no randomized clinical trials have addressed the potential benefits of screening mammography in women older than 75 years. Furthermore, organizational guidelines regarding the appropriate upper age limit for screening, if any, vary.1 Similarly, breast density is increasingly the subject of research in younger women, but very few studies address the risk of breast cancer due to breast density in older women. This timely work by Advani et al2 highlights the intersection of these 2 subjects, which have garnered considerable lay public, health policy, and academic interest in the past several years. In their prospective cohort study of 193 787 women aged 65 years and older from the population-based Breast Cancer Surveillance Consortium, the authors investigated the association of breast density with invasive breast cancer risk in women older than 75 years. They also evaluated the potential role of body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) in modifying the association between breast density and breast cancer risk, with the overarching goal of identifying subpopulations of older women who may benefit from screening. Nearly 35% of the included 221 714 screening mammograms occurred in women aged 75 years or older. Among the 143 118 women aged 65 to 74 years, 45 950 women (32.1%) had dense (ie, heterogeneous or extremely dense) and 97 168 (67.9%) had not dense (ie, fatty or scattered) breasts. Among 78 596 women aged 75 years and older, 23 981 (30.5%) had dense and 54 615 (69.5%) had not dense breasts. The authors found that compared with those with scattered fibroglandular densities, women with dense breasts were more likely to be Asian, less likely to have benign breast disease, more likely to have a BMI between 18.5 and less than 25, and more likely to report current use of hormone therapy. Breast density remained weakly associated with increased breast cancer risk among older women regardless of BMI. The authors also found that the association between breast density and breast cancer risk was similar in direction but slightly weaker in magnitude among women aged 75 years or older vs those aged 65 to 74 years. Despite a decrease in breast density by age, density continued to be associated with a modest increase in breast cancer risk among older women in both age groups (ie, 65-74 and ≥75 years). Notably, the association between density and breast cancer was statistically significant after adjustment for BMI and other risk factors.

The authors’ findings supplement those of prior publications. Although there is a linear association between age and mammographic density, age is not a perfect surrogate for the latter, and there are meaningful numbers of older women with mammographically dense breast tissue.3 A woman in the United States who lives to age 75 years has an average life expectancy of 12 to 14 additional years.4 The incidence of breast cancer increases with age, and given that the data support at least a modest association between breast cancer risk and breast density in older women, continuation of screening mammography in healthy women aged 75 years or older may offer a substantial opportunity to avoid morbidity and mortality from breast cancer in this age group. Screening mammography performance improves with age, demonstrating a higher invasive cancer detection rate and a significantly higher sensitivity and specificity in older women.4 Thus, women older than 75 years have fewer false-positive mammograms and fewer false-positive biopsies. Overdiagnosis is real and remains a concern, however. A study of the benefits and risks of screening mammography in older women with a focus on overdiagnosis5 demonstrated a range of 7.8 to 11.4 life-years gained per 1000 screenings at age 74 years vs 4.8 to 7.8 life-years gained at age 80 years, decreasing to 1.4 to 2.4 life-years gained at age 90 years. The benefits of screening outweighed risks until age 90 years.5

The American Cancer Society, the American College of Radiology, and the Society of Breast Imaging do not recommend stopping screening solely based on age.6 The benefits of screening mammography may take years to be fully realized and decrease when significant comorbidities are present.7 Therefore, screening recommendations should account for life expectancy and comorbid conditions, with screening mammography remaining appropriate when a woman’s life expectancy exceeds 5 to 10 years7 and when treatment would be sought for a new breast cancer diagnosis.

Breast density and age are only a few of the many factors currently under investigation in the drive toward risk-based or personalized breast cancer screening. We must remain cautious in the application of restrictive screening for women of any age with supposedly lower than average risk, because most breast cancers are still diagnosed in women of all ages with no previously identified major risk factors. Ultimately, the decision of when to stop screening is personal, and each woman deserves the agency to weigh her own wishes, values, and life experiences with an accurate and unbiased discussion of risks and benefits of screening mammography in making that decision.

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Article Information

Published: August 26, 2021. doi:10.1001/jamanetworkopen.2021.24385

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2021 Tuite CM. JAMA Network Open.

Corresponding Author: Catherine M. Tuite, MD, Section of Breast Radiology, Department of Radiology, ChristianaCare Helen F. Graham Cancer Center and Research Institute, 4701 Ogletown Stanton Rd, Newark, DE 19713 (catherine.tuite@christianacare.org).

Conflict of Interest Disclosures: None reported.

References
1.
Mack  DS, Lapane  KL.  Screening mammography among older women: a review of United States guidelines and potential harms.   J Womens Health (Larchmt). 2019;28(6):820-826. doi:10.1089/jwh.2018.6992 PubMedGoogle ScholarCrossref
2.
Advani  SM, Zhu  W, Demb  J,  et al; Breast Cancer Surveillance Consortium.  Association of breast density with breast cancer risk among women aged 65 years or older by age group and body mass index.   JAMA Netw Open. 2021;4(8):e2122810. doi:10.1001/jamanetworkopen.2021.22810Google Scholar
3.
Checka  CM, Chun  JE, Schnabel  FR, Lee  J, Toth  H.  The relationship of mammographic density and age: implications for breast cancer screening.   AJR Am J Roentgenol. 2012;198(3):W292-5. doi:10.2214/AJR.10.6049 PubMedGoogle Scholar
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Lee  CS, Moy  L, Joe  BN, Sickles  EA, Niell  BL.  Screening for breast cancer in women age 75 years and older.   AJR Am J Roentgenol. 2018;210(2):256-263. doi:10.2214/AJR.17.18705 PubMedGoogle ScholarCrossref
5.
van Ravesteyn  NT, Stout  NK, Schechter  CB,  et al.  Benefits and harms of mammography screening after age 74 years: model estimates of overdiagnosis.   J Natl Cancer Inst. 2015;107(7):djv103. doi:10.1093/jnci/djv103 PubMedGoogle Scholar
6.
Monticciolo  DL, Newell  MS, Hendrick  RE,  et al.  Breast cancer screening for average-risk women: recommendations from the ACR Commission on Breast Imaging.   J Am Coll Radiol. 2017;14(9):1137-1143. doi:10.1016/j.jacr.2017.06.001 PubMedGoogle ScholarCrossref
7.
American Cancer Society. American Cancer Society recommendations for the early detection of breast cancer. Updated April 22, 2021. Accessed July 18, 2021. https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/american-cancer-society-recommendations-for-the-early-detection-of-breast-cancer.html
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