Adherence to endocrine therapy in women with breast cancer: development and preliminary validation of the A-BET questionnaire

Purpose. To develop an Italian tool that measures the therapy adherence of women with breast cancer undergoing treatment with oral endocrine therapy. Methods A two-phase study was conducted, which followed the guidelines of the European Statistical System for the development and validation of a questionnaire. In the first phase, the questionnaire was developed; in the second phase, a preliminary validation was carried out on patients with breast cancer undergoing treatment with oral hormonal therapies. Results In its final version, the questionnaire presents 6 main items which aim to investigate the level of adherence, the degree of awareness of the nature of the drug taken and the reasons that may influence non- adherence. 82 patients were recruited in the validation study, with an average age of 56.4 years, while for the re-test 40 were selected with an average age of 57.3 years. Content validity reported excellent results. Cronbach's alpha of each item showed a strong degree of correlation. Conclusions. The creation of a tool for measuring adherence to endocrine therapy in breast cancer patients can be a valuable support for healthcare professionals involved in their care. Future studies should be aimed at using A-BET (Adherence – Breast Endocrine Therapy) on larger cohorts of patients in order to verify its validity / reliability more accurately and to be able to generalize the results.