According to the European Society of Parental and Enteral Nutrition (ESPEN) guidelines, malnutrition is diagnosed in patients with BMI <19.8, albumin levels <3.0, and transferrin levels <1.5, but in elderly lung cancer patients undergoing surgical treatment, cardiorespiratory function and the extent of resection should also be evaluated. The gene discussed is ALB; the disease is nutritional deficiency disease.