Assessing Quality of Life with the Novel QLQ-CAX24 Questionnaire and Body Composition Parameters in Rectal Cancer Patients: A Single-Center Prospective Study

Background: Patients with rectal cancer (RC) are at risk of developing cancer-related cachexia, a complex metabolic syndrome that can negatively impact quality of life (QoL), treatment tolerance, and clinical response. Objectives: The aim of the study was to explore the possible associations of the novel European Organization for Research and Treatment of Cancer QoL Questionnaire—Cancer Cachexia (EORTC QLQ-CAX24) scores with body composition parameters and physical performance in patients with locally advanced RC (LARC). Methods: This prospective observational study involved RC patients evaluated at the dedicated outpatient clinic of Clinical Nutrition at the Fondazione Policlinico Agostino Gemelli IRCCS. Patients with a confirmed diagnosis of LARC were enrolled between January and December 2023. The body composition parameters were measured using the preoperative computed tomography scan at the level of the third lumbar vertebra as well as using bioimpedance analysis before and after the radiotherapy treatment. QoL was measured by the EORTC QLQ-C30 and EORTC QLQ-CAX24 questionnaires. Results: A total of 56 RC patients were enrolled. Significant associations (p < 0.05) were found between EORTC QLQ-CAX24 values and the presence of cachexia, body composition, handgrip strength, and malnutrition diagnosis. Muscle mass was significatively also associated with EORTC QLQ-CAX24 results, suggesting a link between subjective perception of QoL and objectively measured body composition. Conclusions: The EORTC CAX24 questionnaire can be an effective tool for monitoring changes in cachexia status during radiotherapy, enabling early detection of cachexia-related complications and timely intervention.