This randomized controlled trial aims to evaluate the effect of personalized pharmaconutrition therapy on myosteatosis, sarcopenia, and disease prognosis in patients undergoing surgery due to gastric cancer. Myosteatosis refers to the accumulation of fat within skeletal muscle and is an important indicator of muscle quality and may be associated with postoperative recovery and disease outcomes.

A total of 40 patients will be included in the study (20 controls, 20 intervention). In addition to standard nutritional care, the intervention group will receive an amino acid-based pharmaconutrition protocol containing glutamine, arginine, and beta-hydroxy-beta-methylbutyrate. The pharmaconutritional intervention will be dosed according to individual requirements so that the total protein intake from the diet is 1-1.5 g/kg, based on the analysis of weekly food consumption records taken from the start to the end of the study. The control group will receive only standard nutritional care.

Myosteatosis, an indicator of muscle quality, will be assessed using computed tomography (CT) images obtained at the level of the third lumbar vertebra (L3). For the evaluation of myosteatosis, the mean radiodensity of skeletal muscle within the range of -29 to +150 Hounsfield Units (HU) will be used. Sarcopenia will be determined using the skeletal muscle index (SMI), which is calculated by dividing skeletal muscle area (SMA) by the square of height (cm²/m²). In addition, clinical and nutritional parameters will also be evaluated.

Measurements will be performed at one week before surgery and at postoperative week 4. Disease prognosis will be evaluated using the Glasgow Prognostic Score and the Prognostic Nutritional Index. The aim of this study is to determine the effects of personalized pharmaconutrition therapy on myosteatosis, sarcopenia, disease prognosis, and clinical outcomes in patients with gastric cancer.

Research Question: Does personalized pharmaconutrition therapy affect myosteatosis and sarcopenia in patients undergoing gastric cancer surgery?

Inclusion Criteria:

• Male adults aged between 18 and 64 years
• Diagnosed with primary or recurrent gastric cancer and eligible for surgery
• Body Mass Index (BMI) within the normal range (18.5-24.9 kg/m²)
• Capable of oral or enteral feeding
• Provided written informed consent

Exclusion Criteria:

• Absence of written informed consent
• Female sex
• Diagnosis of a benign tumor or a tumor located outside the stomach
• Not requiring surgical intervention
• Presence of renal failure or hepatic failure
• Presence of overt ascites or edema within the past month
• Prior use of the pharmaconutrition product planned for this study