Development of a FKSI-23: A new bespoke health-related quality of life (HRQOL) questionnaire for the advanced and adjuvant setting in renal cell carcinoma (RCC).

526 Background: Existing HRQOL measures may not fully capture the experiences of patients with localized and advanced RCC. This study aimed to develop a validated, patient-centered HRQOL metric by incorporating insights from patients, advocates, and clinical experts for both localized and advanced RCC. We previously developed a questionnaire for advanced RCC (Bergerot et al., JCO 2024). In this study, we integrate it into the FKSI-19 model and create a new questionnaire. Methods: A four-phase approach was used. Previous work in advanced RCC assessed item relevance from established HRQOL measures (FKSI-19, EORTC QLQ-C30, EQ-5D), refined through patient feedback and expert review. This phase expanded to include localized RCC in the adjuvant setting. In Phase 1, patients with localized RCC rated the the relevance of 54 items from the metastatic cohort. Phase 2 included a panel of 11 expert refining the adjuvant-specific items. Phase 3 gathered feedback from patient advocates, and Phase 4 further refined the items by harmonizing them with the FACT library for consistency across RCC stages. Results: In Phase 1, 6 of 54 items were rated as most relevant by patients with localized RCC. Phase 2 refined these further, excluding redundant items and adding 4 new questions focused on adjuvant therapy. Phase 3 led to minor revisions after advocate review, and Phase 4, the new items were harmonized with validated FACT library questions. The final adjuvant-specific questionnaire comprises 10 items, addressing concerns such as long-term side effects, surveillance anxiety, and post-surgery emotional distress. The advanced-specific version includes 13 items. Both versions deemed to be of utmost importance to patients with localized and advanced disease. These items can be used as standalone scoring options, resulting in the creation of a novel FKSI-23 metric, allowing for customized questionnaires tailored to specific clinical scenarios. Conclusions: Through collective input from patients, advocates and experts, novel items that aid in capturing the experience of RCC patients were identified and existing metrics were refined to generate separate “scoring options” for patients with localized and metastatic disease. Validation of the resulting FKSI-23 tool is underway in forthcoming studies in RCC.