Adherence to endocrine adjuvant therapy in women with early hormone-positive breast cancer

Abstract

Objective: This study aimed to evaluate adherence to adjuvant endocrine therapy in women with early breast cancer and explore its relationships with patients’ clinical and social characteristics and site of treatment. Methodology: Women with a past history of early-stage estrogen-receptor-positive invasive carcinoma of the breast on adjuvant endocrine therapy for at least 6 months were invited to participate in this study. Adherence was assessed with the questionnaire MMAS8. Demographic and clinical information was reviewed from medical records. Data collection was performed using the RedCap software, and statistical analyses were performed using the R software (R Core Team, 2022). Results: From June 2021 to March 2023, a total of 212 patients were recruited in 6 institutions. The median age was 56 years. Notably, 29.2% were black, 24.1% were premenopause, 38.2% had stage I disease, 65.1% received chemotherapy, and 16.5% received HER2 blockade. The mean duration of endocrine therapy use was 3.7 years. A total of 115 (54.2%) patients used aromatase inhibitors. Notably, 24 (11.4%) patients had low adherence, 76 (36.5%) had intermediate, and 111 (52.6%) had high adherence to adjuvant endocrine therapy. There is a tendency that more postmenopausal women were classified in high adherence grupo than premenopausal women (55.9% vs. 42% p=0.19). There is a tendency that more women in public service had higher adherence than women in private service (59.3% vs. 50.3% p=0.07). There was no difference in adherence in relation to ethnicity and type/duration of endocrine treatment. Conclusion: This study for the first time shows that high adherence to endocrine therapy only happens in 52.6% of patients, lower than reported in previous studies. This result draws attention because it can compromise survival. We will continue the recruitment of patients in the private service and in the public service to assess the rate of adherence in a larger population and the relationship with demographic characteristics.