Factors influencing the first and the fifth years adherence to adjuvant endocrine therapy in breast cancer patients in a low income country

Breast cancer is the leading cause of cancer death in Brazil and in many countries around the world. In order to minimize the risk of recurrence and death, adjuvant endocrine therapy (AET) is used in women whose tumors express hormone receptors; however, the therapy is associated with low rates of compliance. Therefore, we sought to evaluate the proportion of patients who are adherent/non-adherent to AET at the beginning of the therapy (1st year) and at its end (5th year).

Cross-sectional study assessing adherence through the Brief Medication Questionnaire.

It was identified that eventual failures in maintaining the correct adherence to the treatment have risen from 23% of patients in the 1st year of treatment to 35% of patients in the 5th year (p = 0.005). In both groups, use of aromatase inhibitors, polypharmacy of at least 3 mediations and the previous diagnosis of diabetes mellitus (DM) or systemic arterial hypertension (SAH) have contributed to low adherence among patients.

The proportion of patients who are not adherent to AET was high in both cohorts, and the rate of non-adherent patients rises over time. It is essential to incorporate screening methods for lack of compliance to AET, as well as measures to try to reduce non-persistence to the treatment, such as educating the patients on the benefits of the treatment, managing comorbidities through lifestyle changes and, therefore, reducing polypharmacy and, above all, detecting and treating very early the adverse effects of AET that might interfere with its correct use.