[Cases of Malnutrition and Vitamin B1 Deficiency after Gastrointestinal Cancer Surgery].

We experienced cases of malnutrition and vitamin B1 deficiency after gastrointestinal cancer surgery, but they had a good course after vitamin B1 administration. Case 1 is a woman in her 70s who underwent laparoscopic distal gastrectomy for gastric cancer 2 months ago. While under outpatient observation, she was found collapsed at home and urgently brought to the hospital. She lost 3 kg of body weight in 2 weeks and was able to take in oral intake by giving fluids for malnutrition, but was unable to sit up unaided. During the course of hospitalization, vitamin B1 deficiency was reported, and vitamin B1 administration was started, which enabled her to walk independently. Case 2 is a man in her 50s who underwent video-assisted thoracic esophagectomy for esophageal cancer approximately 1 year ago. He was urgently brought to the hospital due to decreased oral intake due to alcohol dependence. 17.1 kg/m2 BMI, malnutrition, 67/40 mmHg blood pressure, and decreased left ventricular septal wall motion were observed. Vitamin B1 deficiency due to alcohol dependence was suspected, so vitamin B1 administration was started, and blood pressure increased within a few hours.