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TOPLINE:

Among women aged 70 years or older with screen-detected breast cancer, those with a history of screening mammography within 5 years of their diagnosis were much more likely to be diagnosed at an earlier stage and much less likely to die from breast cancer, according to a new analysis of over 13,000 women.

METHODOLOGY:

• Biannual screening can help catch breast cancer at earlier stages and reduce breast cancer–specific mortality in women aged 40-74 years who have estrogen receptor (ER)–positive disease; however, there is conflicting evidence on the benefits of biannual screening in older women.
• Researchers analyzed data from the Surveillance, Epidemiology, and End Results-Medicare linked dataset of 13,028 women (aged ≥ 70 years) diagnosed with ER-positive or human epidermal growth factor receptor 2–negative breast cancer between 2010 and 2017. All participants had continuous enrollment in Medicare Parts A and B (fee-for-service) from 5 years prior to 1 year after diagnosis.
• Among the total participants, 77.5% had at least one prior screening mammogram; 31.0% had two mammograms, and 45.6% had three or four mammograms. A total of 22.5% had no prior screening. Screening mammograms were differentiated from diagnostic mammograms using a validated claims-based algorithm.
• The primary outcome was stage at diagnosis, categorized as very early (T1N0) vs later stage (T2+ or N1+). The secondary outcome was breast cancer–specific mortality.

TAKEAWAY:

• Overall, most patients (70.7%) were diagnosed at a very early stage (T1N0), while 29.3% of women were diagnosed with later-stage disease (T2+ or N1+). Patients with prior screening had significantly lower rates of later-stage disease than those with no prior screening (25.1% vs 43.4%).
• Compared with no screening, prior screening was associated with a 54% lower likelihood of being diagnosed at a later stage (adjusted odds ratio [aOR], 0.46). Medicare/Medicaid dual eligibility (aOR, 1.17), higher poverty (aOR, 1.21), and tumors with higher grades (grade 3 or 4 vs grade 1: aOR, 4.90) were also associated with a greater likelihood being diagnosed at a later stage.
• Overall, breast cancer–specific mortality was 4.4%. Deaths occurred in approximately 8% of women with no prior screening and 3.3% of women with prior screening (P < .001).
• Prior screening was associated with a lower risk for breast cancer–specific mortality than no prior screening (adjusted hazard ratio [aHR], 0.63). In addition, having three to four prior mammograms was also associated with a lower risk for breast cancer–specific mortality than having one prior mammogram (aHR, 0.63). Women aged 85 years or older had a higher risk for breast cancer–specific death than those aged 70-74 years (aHR, 2.28).

IN PRACTICE:

“Our findings support the potential for routine screening to improve breast cancer outcomes” and “highlight the importance of considering screening history when evaluating the impact of regular mammography among older women,” the study authors wrote.

SOURCE:

The study, led by Sida Huang, BS, Yale School of Public Health, New Haven, Connecticut, was published online in JAMA Network Open.

LIMITATIONS:

The study used a claims-based algorithm to categorize mammograms, which could have led to some misclassification. However, the researchers noted that focusing on women with screen-detected breast cancer should reduce confounding from non–screen-detected cancers. The study did not account for breast density and family history, or other clinical factors, and its findings may be influenced by lead-time bias.

DISCLOSURES:

The study received support through grants from the American Cancer Society and was partly funded by the Yale Cancer Center Pilot Award for Research on Cancer Equity. Some authors reported receiving grants or personal fees from various sources.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.