To evaluate variations in the use of adjuvant endocrine therapy (AET) by race and geography, this research examined their influence on initiation and adherence to AET in female Medicare enrollees with breast cancer, diagnosed between 2007 and 2011.
Using SEER (Surveillance, Epidemiology, and End Results Program)-Medicare data from 2007 to 2001, logistic regressions with random intercept for county of residence were used to predict AET initiation during 1st year and AET adherence assessed by the medication possession ratio (MPR) during year after initiation in a sample of fee-for-service medicare beneficiaries. Part D enrollment was required for the examination of adherence. Independent variables examined were race (black, white, or other) and geographical indicators (area deprivation, non-metropolitan status, and physician shortage).
Overall, 23% of patients did not initiate AET within 1 year and 26% of the initiation sample was not adherent to AET, with average follow-up time among initiators of 141 days and an average MPR of 0.84. Significant heterogeneity (P < .01) was found between SEER sites, with initiation rates as low as 69% for Washington and as high as 81% for New Jersey; MPR adherence varied from 77% in New Jersey to 68% in Utah.
Blacks had lower initiation, enrollees not in Medicaid had lower adherence, lower area deprivation counties had lower initiation, earlier SEER-Medicare years had both later initiation and nonadherence, and significant (P < .05) variations between SEER sites remained after accounting for area deprivation index, metropolitan status, and physician shortage. Subgroup analysis showed particular pockets of lower initiation for blacks with stage III tumors, on chemotherapy and lower adherence for blacks in youngest age group, with stage III tumors, tamoxifen use and blacks/others in oldest age group.
Black women and women living in states with more rurality in the United States were less likely to receive guideline-recommended AET, which necessitates future efforts to alleviate these disparities to improve AET use and ultimately pursue more survival gains through optimizing adjuvant treatment use among cancer survivors.