Adherence to adjuvant endocrine therapy in postmenopausal breast cancer patients: A 5-year prospective study

Purpose: Adjuvant endocrine therapy (ET) in breast cancer reduces recurrence risk and increases overall survival. The aim of the study was to quantify non-adherence and discontinuation to ET in postmenopausal women with breast cancer, and identify possible clinical or social risk factors. Methods: Women with hormone-receptor positive breast cancer (N = 138), mean age 58 (SD 9.3) years, filled in 4 questionnaires within 1-12, 24, 36 and 48-60 months after surgery; Subjective Health Complaints Inventory (SHC), Functional Assessment of Cancer Therapy-Social Support Subscale (FACT-ES), and Quality of Patient Information Questionnaire (QPI). Adherence to Tamoxifen (Tam) or Aromatase Inhibitors (AI) was examined using the self-reported Morisky Medication Adherence Scale (MMAS-8) and data from the Norwegian Prescription Database (NorPD). Kaplan-Meier curves and Cox proportional hazards regression models estimated adherence to ET. Results: The estimate of discontinued ET within 60 months was 38%. Self-reported discontinuation was 7% compared with 25% from the NorPD. Being overweight or obese were significantly time dependent factors predictive for discontinuing ET, p = 0.025. Conclusion: Closer follow-ups, tailor-made information about the proven benefits of ET, and keeping a normal body mass index (BMI) may improve adherence to ET in postmenopausal women with breast cancer. (C) 2019 Elsevier Ltd. All rights reserved.