Nutrition plays a major role in cancer development and treatment. Malnutrition is a significant and common problem in cancer patients and has been recognized as an important component of adverse outcomes, including increased morbidity and mortality. At the time of diagnosis, the majority of patients with upper gastrointestinal cancer, including those having undergone gastrectomy, have already suffered from significant nutritional deficiencies. Therefore, optimization of nutritional status can help cancer patients maintain the body's nutrition stores and improve symptoms such as anemia and neuropathy that may be associated with nutritional deficiencies. Depending on the etiology of symptoms, iron or Vitamin B12 (injection or oral) may be given. Early recognition and detection of risk for malnutrition may be performed using nutrition screening followed by comprehensive assessments. The most effective approach to malnutrition and nutritional deficiency is the prevention of its initiation through nutrition monitoring and intervention.