Adherence to Aromatase Inhibitor Therapy in Breast Cancer: Insights From a Multicenter Italian Study

In estrogen-receptor positive breast cancer (BC), oral adjuvant endocrine therapy (ET) administered for at least 5 years significantly reduces risks of disease recurrence and mortality. Among available therapies, aromatase inhibitors (AI) showed high efficacy. However, adherence to ET is very poor. Effective support by physicians requires the identification of factors influencing AI treatment adherence.

A prospective/retrospective multicentric study was conducted in adult BC women currently undergoing adjuvant treatment with AI. Study endpoints were assessed through a questionnaire after at least 12 months of adjuvant therapy. The primary objective was the assessment of the adherence to AI; secondary objectives were the assessment of adverse events (AEs) of the therapy and the solutions adopted for AEs.

Overall, 903 patients with a median age of 63 years were enrolled. Two hundred and forty-three patients (26.9%) stated they do not respect the intake times. Adherence was not influenced by the number of drugs other than the ones for BC or by age. Most patients (87%) suffered from one or more AEs. The most frequent are musculoskeletal symptoms, which occurred in 86.2% of the patients. 74.5% and 74.4% of participants reported hot flashes and tiredness, respectively. No structured or uniform responses were reported regarding the strategy for solving side effects: answers were almost generic, but for more than 50% of patients, the final outcome was positive. AEs were a driver for nonadherence in only 19.6% of patients.

Survey results should be considered as an overview of AI therapy adherence in BC patients. We showed that the oncologist has a key role in improving therapeutic adherence and, as a consequence, in improving clinical outcome. Through a dialogue with the patient and a synergistic interaction with other clinical specialists, a greater awareness of the importance of the treatment could be warranted.