Background: Estrogen receptor positive (ER+) and progesterone receptor positive (PR+) cancers account for the majority of breast cancer diagnoses and deaths. Among women with ER+ or PR+ breast cancers, endocrine therapy (ET) is the cornerstone of adjuvant therapy and reduces 5-year risk of recurrence by as much as 40%. Observational studies in Medicare and privately-insured populations suggest that ET is underutilized. We sought to characterize ET use in a low-income Medicaid-insured population in North Carolina.
Methods: We used Medicaid claims data matched to NC Central Cancer Registry records for women ages 18-64 diagnosed with in situ, stage I or II breast cancer from 2003-2007. We excluded dual eligibles and included only cases enrolled in Medicaid for at least 12 of the 15 months following the index diagnosis. We defined our outcome as receipt of any ET medication (tamoxifen, letrozole, exemestane, or anastroxole) in prescription claims during the 15-month period post-diagnosis, among women with ER+ or PR+ disease. In multivariate logistic regressions, independent variables included age, race, tumor characteristics, receipt of other breast cancer treatments, co-morbidity, rural/urban residence, reason for Medicaid eligibility, involvement in the Breast and Cervical Cancer Control Program (BCCCP), patient-centered medical home enrollment, and diagnosis year.
Results: Of the 269 women who met inclusion/exclusion criteria and were ER+ or PR+, only 45% filled a prescription for ET during the study period. In multivariate analyses, being involved in the CDC-affiliated BCCCP was significantly associated with higher likelihood of receipt of guideline-recommended endocrine therapy (Marginal Effect: 0.299, p<0.01), but other independent variables were not significantly correlated with receipt of ET.
Conclusions: Results suggest that ET is substantially underutilized in this low-income, vulnerable population and that intervention efforts to improve ET use may be important. Qualitative research is needed to understand the more nuanced, behavioral reasons for ET underuse, which may be related to symptom burden, cost, and patient-provider communication.
