A questionnaire form containing general information, dietary habits, and food consumption records will be applied by the researcher in the preoperative period to the patients who volunteered to participate in the study. Body composition will be taken by bioelectrical impedance analysis method. Hand grip strength will be taken with a digital hand dynamometer. The nutritional status of patients will be assessed using the criteria of the Nutritional Risk Screening 2002 (NRS-2002) and the Global Leadership Initiative on Malnutrition (GLIM). For body composition analysis, computed tomography images, known as the gold standard, will be used in cancer patients. Computed tomography images of the patients will be obtained from hospital records at L3 lumbar vertebra level. The software program ImageJ developed by the US National Institute of Health will be used to calculate the visceral fat area (cm2), subcutaneous fat area (cm2), and skeletal muscle area (cm2) from the recorded images.
Preoperative biochemical parameters will be obtained from hospital records. The systemic inflammatory response will be determined by the Prognostic Nutritional Index, Neutrophil Lymphocyte Ratio, and Delta Neutrophil Index. The inflammatory load of the diet will be calculated using the Dietary Inflammatory Index. The quality of life of patients will be assessed using cancer-specific scales developed by the European Organisation for Research and Treatment of Cancer (EORTC) during the preoperative and postoperative periods. These scales are EORTC-QLQ-C30 for general quality of life and EORTC-QLQ-CR29 for colorectal cancer-specific quality of life.
