Abstract P3-12-02: Predictors of adherence to adjuvant endocrine therapy (ET) for early breast cancer (BC) in a prospective clinic-based cohort

Abstract

Abstract Background: Adjuvant ET is associated with improved survival in women with hormone receptor-positive early BC. Nonetheless, more than a quarter of women are non-adherent or discontinue therapy early. We aimed to identify whether baseline characteristics and changes in weight and patient-reported outcomes (PRO) early during the course of ET are associated with medication adherence behavior (MAB) in a prospective cohort. Methods: We enrolled women initiating or switching adjuvant ET for stage 0-III BC in a prospective clinic-based cohort. Participants completed PRO questionnaires at baseline, and 3, 6, and 12 months (mo) after initiating ET. PRO questionnaires included FACT-ES, the NIH PROMIS measures for pain interference, fatigue, depression, anxiety, physical function, and sleep disturbance, and the MOS Sexual Functioning Scale. MAB was assessed by the Medication Adherence Questionnaire (MAQ). MAB was defined as high (MAQ score=0), or medium/low (MAQ score>0). Questionnaires were administered through the PatientViewpoint web-based interface. We tested changes in mean PRO scores from baseline to follow-up time points with paired t-tests. We explored associations between baseline characteristics, and changes in weight and PRO at 6 mo with MAB at 12 mo using Fisher's exact test, Wilcoxan rank sum tests and t-tests. P-values <0.05 were considered significant. Results: From March 2012 to December 2016, 336 women enrolled in the cohort. Mean age was 60 (range 26-90), 84% were Caucasian, and 67% were post-menopausal. Overall, 57% received an aromatase inhibitor, 43% received tamoxifen, and 28% received prior taxane chemotherapy. Median follow-up was 12 mo. At baseline, 61% were overweight/obese, and 21% gained >5% of baseline weight by 12 mo. Mean baseline and follow-up scores at 3, 6 and 12 mo were within 1 standard deviation of reference population means for all PRO measures. Compared to baseline, endocrine symptoms were increased at 3, 6 and 12 mo (p<0.05), while sexual function and depression did not differ between baseline and any follow-up time point (p>0.05). At 6 mo, anxiety was reduced, physical function was improved and pain impact was reduced compared to baseline (p<0.05). MAB was high for 71% of participants at 12 mo. Preliminary data demonstrate that, compared to those with high MAB at 12 mo, women with medium/low MAB at 12 mo took fewer concomitant medications at baseline, and had more improvement in anxiety and sexual function at 6 mo. MAB at 12 mo did not differ according to race, type of ET, baseline weight or PRO measures, or 6 mo change in weight or other PRO measures. Conclusions: Early changes in anxiety and sexual function during the course of adjuvant ET and the number of baseline concomitant medications may separate women with subsequent high versus medium/low MAB risk. Weight loss interventions and symptom management are needed for women receiving adjuvant ET during the first year of treatment. Our data will be used to create a model to predict MAB for validation studies and as the basis to devise interventions to improve adherence to adjuvant ET. Citation Format: Smith KL, Yeruva SLH, Blackford A, Huang C-Y, Westbrook KE, Harding BA, Smith A, Fetting J, Wolff AC, Jelovac D, Miller RS, Connolly R, Armstrong D, Nunes R, Visvanathan K, Stearns V. Predictors of adherence to adjuvant endocrine therapy (ET) for early breast cancer (BC) in a prospective clinic-based cohort [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-12-02.