The aim of this study was to evaluate the impact of the preoperative body mass index (BMI) on the postoperative outcomes in patients with completely resected non-small cell lung cancer (NSCLC).

The data of patients with NSCLC in whom R0 resection was achieved were extracted from the database of NSCLC samples accumulated by the Japanese Joint Committee of Lung Cancer Registry in the year 2010, and the surgical outcomes including postoperative morbidity, mortality and the prognosis, were evaluated.

Among 18,978 registered lung cancer cases, 16,509 patients (9996 men and 6513 women) were extracted. The median of age was 69 years old, and the histologic types included adenocarcinoma (n = 12,029), squamous cell carcinoma (n = 3286), large-cell carcinoma (n = 488) and others. The patients were divided into three groups according to their BMI: normal (BMI 18.5 to <25), underweight (BMI < 18.5) and overweight (BMI ≥ 25). Multivariate logistic regression analyses of factors associated with postoperative morbidity and mortality showed no significant differences among the three groups. In comparison to the normal group, the overall survival (OS) of the underweight group was significantly worse (p < 0.001) while that of the overweight group was marginally better (p = 0.075). A multivariate analysis of factors associated with OS showed that in addition to the age, sex and clinical stage, the preoperative BMI (underweight group vs. normal group: hazard ratio [HR] 1.417 [95% confidence interval {CI}: 1.278-1.572, p < 0.001], overweight group vs. normal group: HR 0.883 [95% CI: 0.806-0.967, p = 0.007]) was an independent prognostic factor. A multivariate analysis for the disease-free survival (DFS) also showed the preoperative BMI to be an independent significant prognostic factor.

The preoperative BMI is an independent prognostic factor in patients with completely resected NSCLC. A low preoperative BMI was associated with significantly poor survival in Japan.