High out-of-pocket costs, rather than race/ethnicity, may impact adjuvant endocrine therapy adherence

High out-of-pocket costs, rather than race or ethnicity, are responsible for disparities associated with adherence to adjuvant endocrine therapy, according to a new study from researchers at The University of Texas Health Science Center at Houston (UTHealth) School of Public Health.

Adjuvant endocrine therapy (AET) is treatment given after surgery, chemotherapy or radiation therapy to lower the chance of breast cancer recurrence for hormone receptor-positive breast cancer patients.

Previous research has found that rates of adherence to breast cancer treatment vary by race and ethnicity and that African American and Hispanic woman are least likely to adhere to recommended AET. In a new study published today in the Journal of Clinical Oncology, UTHealth researchers found that after controlling for out-of-pocket costs, race and ethnicity were not predictors for adherence to AET. Instead, socioeconomic status and high out-of-pocket costs were responsible for low adherence to treatment.

"This finding is highly important to the general public because it adds to the evidence that little to no-cost prescription drugs may be an effective strategy for AET adherence rates. The improved adherence to AET could reduce the risk of breast cancer recurrence and mortality," said Albert J. Farias, Ph.D., M.P.H., first author and postdoctoral research fellow at UTHealth School of Public Health.

Farias and Xianglin Du, M.D., Ph.D., senior author and professor in the Department of Epidemiology, Human Genetics and Environmental Sciences at the School of Public Health, used data from 8,688 patients in the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Medicare-linked database and Medicare Part-D claims. They found that 62 percent of women were adherent to AET for the first year after diagnosis.

AET treatment includes tamoxifen and the aromatase inhibitors (AIs) exemestane, anastrozole and letrozole. The National Comprehensive Cancer Network recommends that post-menopausal women diagnosed with hormone-receptor positive, early-stage breast cancer receive either an AI as initial adjuvant therapy for five years, or tamoxifen for two to three years followed by an AI to complete five years, or tamoxifen alone for five years. The AET medication is taken orally.

"Most of the differences that we see by race or ethnicity in adherence to AET were explained by the out-of-pocket costs of the drugs to patients when filling prescriptions for AET medications," said Farias.

The mean out-of-pocket cost for a 30-day supply of medication in the sample was $52.40. Half of the study population paid less than $27.05 for a 30-day supply of medication.