Impact of Smoking, Alcohol Use and Exercise on Underweight after Gastrectomy: A Nationwide Cohort Study of Gastric Cancer Patients in Korea.

Background/Aims: Weight loss following gastric cancer (GC) surgery is a prevalent and significant long-term complication that impacts the patient's oncologic prognosis and quality of life. The impact of lifestyle changes after surgery with regard to regular exercise, smoking, and alcohol consumption on weight loss have not been fully explored. We studied the factors associated with underweight (body mass index <18.5 kg/m Methods: We utilized a population-based cohort provided by the Korean National Health Insurance Service, which included cancer screening data. In total, 27,854 patients who underwent GC surgery between 2010 and 2016 were included. Results: Among the 27,854 patients in the study cohort, 3,064 (11.0%) were underweight. Female sex (odds ratio [OR], 1.74; 95% confidence interval [CI], 1.55 to 1.96; p<0.001) was a significant risk factor for becoming underweight postoperatively. Engaging in regular exercise (OR, 0.73; 95% CI, 0.60 to 0.89; p=0.002) and ceasing smoking (OR, 0.31; 95% CI, 0.13 to 0.78; p<0.001) emerged as substantial preventive factors against becoming underweight, particularly in female patients. Exercise (OR, 0.76; 95% CI, 0.65 to 0.89; p=0.001) proved more beneficial for patients aged <65 years. Conclusions: Smoking cessation and regular exercise are associated with a reduced risk of postoperative underweight in GC patients following gastrectomy.