Prognostic value of body mass index and change in body weight in postoperative outcomes of lung cancer surgery

OBJECTIVES: Nutritional status is associated with an effect on oncological outcomes. However, the effect of nutritional status on postoperative survival in lung cancer has not been well studied. We retrospectively analysed and evaluated the effect of preoperative body mass index (BMI) and changes in body weight on postoperative outcomes of lung cancer surgery. METHODS: A total of 1311 patients with non-small-cell lung cancer who underwent surgery between January 2001 and December 2011 were included in this study. Preoperative body weight at 4-12 weeks prior to surgery was obtained in 737 patients and the ratio of change in body weight was calculated. RESULTS: The patients were classified into four groups as follows: underweight (BMI < 18.5), normal weight (BMI from >= 18.5 to < 25), overweight (BMI from >= 25 to < 30) and obese (BMI >= 30). Postoperative survival curves of the BMI groups showed that the underweight group had a poorer prognosis than the other groups, especially for disease-free survival (DFS) (P = 0.03). Univariate and adjusted survival analyses using Cox's proportional hazards regression model showed that low BMI was a significantly poor prognostic factor in overall survival (OS) (P = 0.03 and P = 0.02, respectively) and DFS (P < 0.01 and P < 0.01, respectively). Among the BMI groups, the underweight group had a significant worse prognosis than the other groups for DFS in univariate and adjusted analyses (P = 0.04 and P < 0.01, respectively). With regard to changes in body weight, patients with a body weight loss of 3.7% or greater had a significantly poorer prognosis for OS and DFS in univariate analysis and for DFS in adjusted analyses compared with the other patients. Regarding short-term outcomes, the weight loss group had a significantly longer postoperative hospital stay than the non-weight loss group (P = 0.02) and postoperative 90-day mortality was significantly lower in the normal weight group than in the underweight group (P = 0.03). CONCLUSIONS: Low BMI and significant body weight loss before surgery have a negative effect on surgical outcomes for patients with non-small-cell lung cancer.