270MO An international update of the EORTC questionnaire for assessing quality of life in breast cancer patients: Results of the validation study phase IV EORTC QLQ-BR42

The EORTC QLQ-BR23, developed in 1996, was one of the first disease-specific questionnaires, to assess quality of life (QoL) in patients with breast cancer (BC). However, since 1996, major changes in BC treatment have occurred, requiring updating of the EORTC BC module. The results of phase I-III were presented at the ESMO Meeting 2018. This abstract presents the final phase IV validation study of the updated version, the EORTC QLQ-BR42. The update of the EORTC QLQ-BR23 module followed standard EORTC guidelines.Developmental phase I-II, a systematic literature review followed by interviews with patients and health care providers, resulted in 15 QoL issues transformed into 27 items relevant for BC patients. The preliminary module of 27 items was pre-tested in phase III toassess their perceived importance and acceptability. Phase IV was designed to assess the psychometric properties of the questionnaire in an international field study. Data of all patients were usedfor psychometric analyses, i.e., the evaluation of the scale structure, internal consistency, test-retest reliability, convergent, discriminant, and clinical validity, and responsiveness to change. The study was registered on clinicaltrials.gov database (NCT04270123). Between May 2019 and September 2021, 576 patients from 17 countries (16 different languages) were enrolled in the international phase IV validation study. The psychometric analyses resulted in a final questionnaire containing 42 items divided into ten scales: Breast Symptoms, Body Image, Sexual Functioning, Arm Symptoms, Systemic Chemotherapy Side Effects, Skin Toxicity/Neuropathy, Musculo/Skeletal Symptoms, Endocrine-related Symptoms, Breast Satisfaction, Vaginal Symptoms, and 3 single items: Weight Gain, Sexual Enjoyment and Future Perspective. The EORTC QLQ BR42 is a revised and innovative module that incorporates the original BR23 items that remain relevant, combined with 19 new items that address the side effects of therapies developed over the past 20 years. This comprehensive module is well suited to assess the QoL of BC patients in future trials.