Screening frequency not a strong risk factor for advanced breast cancer

Key takeaways:

• Pre- and postmenopausal Black and Hispanic women had the highest BMI population attributable risks.
• Breast cancer risk was small for family breast cancer history, breast biopsy history and screening interval.

Among routinely screened women, annual vs. biennial screening was not a strong risk factor for advanced breast cancer and accounted for a small proportion of diagnoses, according to cohort study results published in JAMA Oncology.

“Black and Hispanic/Latinx women are at higher risk of being diagnosed with advanced cancer than white and Asian or Pacific Islander women, and this difference is only partially accounted for by screening utilization,” Karla Kerlikowske, MD, professor in the department of epidemiology and biostatistics at the University of California, San Francisco, and colleagues wrote. “Identifying advanced breast cancer population attributable risk proportions that account for the largest proportion of advanced breast cancers among regular screeners and understanding differences in advanced cancer population attributable risk proportions by race and ethnicity is important for developing personalized, equitable screening strategies and primary preventions.”

Kerlikowske and colleagues conducted a cohort study with data from 904,615 women (median age, 57 years) from Breast Cancer Surveillance Consortium community-based breast imaging facilities from 2005 to June 2018. All women were aged 40 to 74 years and underwent annual or biennial screening mammograms associated with advanced breast cancers diagnosed within 2 years of screenings.

The primary outcomes were heterogeneously or extremely dense breasts, first-degree family history of breast cancer, overweight/obesity, history of benign breast biopsy and screening intervals stratified by menopausal status and race/ethnicity.

Of the 3,331,740 annual or biennial mammogram screenings, there were 1,815 advanced breast cancer diagnoses. In the cohort, 10.8% of women were Asian or Pacific Islander, 9.5% were Black, 5.3% were Hispanic, 72% were white and 2% were of other races/ethnicities.

Postmenopausal women had larger BMI population attributable risk proportions compared with premenopausal women (30% vs. 22%). In addition, postmenopausal Black (38.6%), Hispanic (31.8%) and premenopausal Black (30.3%) women had the highest BMI population attributable risk proportions compared with other races/ethnicities. Premenopausal (84.4%) and postmenopausal (85.1%) Black and Hispanic (72.4%) women had the highest overall prevalence of having overweight/obesity compared with other races/ethnicities.

Breast density population attributable risk proportions were larger for premenopausal women compared with postmenopausal women (37% vs. 24%) and highest among premenopausal Asian or Pacific Islander (46.6%) and white (39.8%) women. Population attributable risk proportions were small for family history of breast cancer (5%-8%), breast biopsy history (7%-12%) and screening interval (2.1%-2.3%) among premenopausal and postmenopausal women.

“Screening mammography randomized clinical trials have shown decreased advanced cancer rates in women aged 50 to 74 years whether women are screened annually or biennially. However, mammography is not sufficient to exclude advanced breast cancer diagnoses,” the researchers wrote. “Primary prevention is also needed and should focus on interventions to assist patients with overweight/obesity to attain normal weight to reduce their risk of poor-prognosis tumors.”