Black women have a persistent disparity in breast cancer survival after controlling for clinical factors, suggesting that differential receipt or efficacy of treatment may contribute to poorer outcomes. Delays in initiating treatment and subsequent spillover effects into time to completion are one proposed mechanism by which these survival disparities may occur.

The Carolina Breast Cancer Study Phase III is a large population-based study of North Carolina women with incident breast cancer. For this analysis, we included black (n=1328) and white (n=1331) women with stage I-III disease whose treatment included surgery with or without adjuvant therapies. Patients were grouped by treatment pathway (surgery only, surgery + chemotherapy, surgery + radiation, or all three modalities). We investigated the association of race with delays in treatment initiation, duration and completion. Delays in initiation of first treatment were modeled in two ways: i) time to initiation >30 days from diagnosis, and ii) time to initiation above the 75th percentile. Extended duration and delay in completion were defined as being > 75th percentile in days between initiation and end of treatment (duration) or days from diagnosis to end of treatment (completion) compared to others in the same pathway. Models controlled for treatment pathway, age, and tumor characteristics. Additional models controlled for demographic factors (marital status, income, education, insurance) and county-level factors related to care access (% urban and health professional shortage area status).

In analyses adjusted only for age at diagnosis, black women had a significantly higher risk of treatment delays whether measured by delay>30 days (risk ratio (RR) 1.24, 95% CI 1.12-1.37) and or by highest quartile of time to initiation (RR 1.23, 95% CI 1.07-1.40) compared to whites. They were also at higher risk of extended treatment duration (RR 1.47, 95% CI 1.29-1.69) and time to completion (RR 1.58, 95% CI 1.37-1.81) compared to others in the same pathway. Interestingly, adjustment for tumor characteristics did not impact effect estimates. While adjustment for demographic factors had little impact on the association of race with delays in initiation, it attenuated the association of race with delays in treatment duration and completion. Further adjustment for care access factors slightly attenuated the association of race with treatment initiation and completion, but did not impact associations with treatment duration. Significant racial disparities remained in delay across all phases of care after adjustment for clinical, demographic and access factors.

Overall, black women were at higher risk of delays in treatment initiation, extended duration and time to completion than white women receiving similar treatment, and these disparities appear to be compounded over the care continuum. These findings suggest that racial differences in income, education and insurance may partly explain observed disparities in treatment duration and time to completion, whereas care access factors may have more impact on disparities in treatment initiation, and interventions that target both patient-level and care access barriers may be needed to improve timely delivery across the care continuum.

Citation Format: Reeder-Hayes KE, Mayer SE, Olshan A, Carey LA, Wheeler SB, Tse C-K, Troester M. Race, place and delays in breast cancer treatment across the care continuum in the Carolina breast cancer study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-10-01.