146O Measuring health-related quality of life in solid rare cancer patients according to EURACAN domains: A progress report of an EORTC Quality of Life group (QLG) study

Patients with a rare cancer report lower health-related quality of life (HRQoL) than common cancer patients. Specific HRQoL measures are required to better assess the unique physical and psychosocial issues faced by rare cancer patients. This EORTC Quality of Life Group (QLG) study investigates how HRQoL is currently measured in clinical research among these patients, identifies HRQoL issues patients face due to the disease's rarity, and evaluates the content validity of EORTC HRQoL questionnaires. Initiated in 2023, here we present an update of the study. A mixed-method study is used by two systematic literature reviews (one on HRQoL measures currently used and one on healthcare experiences) and a global, multicentre study collecting qualitative (interviews) and quantitative (questionnaires) data on HRQoL of rare cancer patients with a solid tumour. The EURACAN domain division is used to analyse HRQoL differences in subgroup of patients. Data from patients and healthcare professionals assess content validity, importance and relevance of items in existing EORTC questionnaires (tumour-specific modules and stand-alone healthcare-related questionnaires). The first review yielded 18,704 articles, with 1416 screened, and 608 data-extracted. Early results reveal the EORTC C30 questionnaire as the most common used HRQoL measurement. Over half of the studies utilize general and tumour-specific instruments. The second review on healthcare system issues has yet to start. Qualitative and quantitative analysis are ongoing. Out of the planned 500 patient interviews and questionnaires, 184 have been completed, enabling analysis in 11 of the 20 EURACAN (sub)domains. Out of 150 planned interviews and questionnaires with healthcare professionals, 114 have been gathered. Preliminary results confirm the lack of specific HRQoL measures for rare cancer patients. The results of the second part of this project will help the development of a guidance document to advise on how to best measure HRQoL in solid rare cancers. Given the large diversity, a flexible strategy is expected (e.g., construction of item lists with validated items from the EORTC QLG Item Library).