Background: Adjuvant treatment with oral hormonal therapy improves clinical outcomes for breast cancer, but women have difficulty adhering to the 5-year regimen.
Objective: The aim of this study was to explore pretreatment predictors of short-term nonadherence to oral hormonal therapy for women with early-stage breast cancer from the pretreatment assessment to 6 months after initiation of hormonal therapy.
Methods: A secondary analysis was performed using data collected from 198 women enrolled in one of two longitudinal studies. Nonadherence was defined as the percentage of prescribed doses of hormonal therapy not taken during the first 6 months of therapy measured using electronic medication event monitoring. Information on predictor variables was measured at pretreatment using self-report and medical record review. Linear regression analysis was performed to examine associations between predictor variables and 6-month nonadherence in a bivariate manner to first identify candidate predictors variables at p < .20 and then multivariately considering candidate predictors identified through stepwise and backward elimination regression methods.
Results: Participants were White (98.3%), well educated (M = 15.0; SD = 2.9 years of schooling), and on average, 59.1 years old (SD = 7.5 years old). Mean nonadherence was 11.3%. Stepwise and backward elimination modeling algorithms identified a similar set of predictors associated with 6-month nonadherence and explained 13.0% of the variance (adjusted R = .11, standard error of the estimate = 0.28). Ductal carcinoma in situ tumor type (p = .004) and higher weight concern scores (p = .003) were associated with nonadherence.
Discussion: The findings suggest that additional examinations of associations of tumor type and symptom burden with nonadherence are indicated.