Socio-demographic and geographic variations in the utilization of hormone therapy in older women with breast cancer after Medicare Part-D coverage.

No study has previously reported the utilization and adherence to hormone therapy for Medicare Part-D beneficiaries with breast cancer. This study was conducted using the Surveillance, Epidemiology, and End Results-Medicare-linked data to assess socio-demographic, geographic, and other variations in the receipt of hormone therapy among patients with hormone receptor-positive breast cancer and to assess adherence to hormone therapy within 1-year follow-up. The percentage of patients who received hormone therapy was calculated and stratified by chemotherapy status (yes or no). Logistic regression models were performed to assess the variations associated with the use of selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), and hormone therapy (SERMs or AIs). Of 25,128 women with hormone receptor-positive breast cancer in 2006-2009 who were enrolled in Medicare Part-D program, 70.8 % received hormone therapy, 22.2 % received SERM, and 56.9 % received AIs. Among those receiving chemotherapy, significant predictors of receiving hormone therapy included age, tumor stage, surgery type, radiation therapy; significant predictors of receiving SERM included race, year of diagnosis, and tumor stage; and significant predictors of receiving AI included age, race, socioeconomic status, geographic location, tumor stage, and radiation therapy. For those without receiving chemotherapy, most of the above factors were significant, but differed across each drug class. In conclusion, over two-thirds of hormone receptor-positive breast cancer patients received hormone therapy, and still 29.2 % of patients did not receive it. Tumor and clinical factors are the most significant predictors for the receipt of hormone therapy.