Purpose: Although United States clinical guidelines differ, the earliest recommended age for average risk breast cancer screening is 40 years. Little is known about factors influencing screening initiation.
Methods: We conducted a cohort study within the National Cancer Institute-funded Population-based Research Optimizing Screening through Personalized Regimens (PROSPR) consortium. We identified 3413 women on their 40th birthday in primary care networks at Geisel School of Medicine at Dartmouth (DH) and Brigham and Women's Hospital (BWH) during 2011-2013 with no prior breast imaging or breast cancer. Cumulative incidence curves and Cox modeling were used to determine time from the 40th birthday to first breast cancer screening, cohort exit, or 42nd birthday. We calculated hazards ratios and 95 % confidence intervals from multivariable Cox proportional hazards models.
Results: Breast cancer screening cumulative incidence by the 42nd birthday was 62.9 % (BWH) and 39.8 % (DH). Factors associated with screening initiation were: a primary care visit within a year (HR 4.99, 95 % CI 4.23-5.89), an increasing number of primary care visits within a year (p for trend <0.0001), ZIP code of residence annual median household income ≤$52,000 (HR 0.79, 95 % CI 0.68-0.92), and health insurance type (Medicaid HR 0.72, 95 % CI 0.58-0.88; Medicare HR 0.55, 95 % CI 0.39-0.77; uninsured HR 0.37, 95 % CI 0.25-0.57).
Conclusions: Breast cancer screening uptake after the 40th birthday varies by health system, primary care visits, median household income, and health insurance type, suggesting the need for further exploration. Future research should evaluate screening performance metrics after initiation and consider cumulative benefits and risks associated with breast cancer screening over time.
Keywords: Breast neoplasms; Early detection of cancer; Mammography; Mass screening; Prevention & control; Primary health care.