Association of body mass index and smoking on outcome of Chinese patients with colorectal cancer

The impact of body mass index (BMI) on the prognosis of patients with colorectal cancer remains largely unknown, particularly in Asian populations. Therefore, the aim of this study was to examine the influence of BMI on clinicopathological characteristics and mortality of Chinese colorectal cancer patients.

The study cohort consisted of 525 patients who were diagnosed with colorectal cancer and underwent radical surgery at the second hospital of Harbin Medical University between June 2004 and August 2011. Study participants were divided into two BMI categories: normal weight (BMI <23 kg/m²) and overweight (BMI ≥23 kg/m²).

Of 525 patients, 208 patients (39.6%) were included in the normal-weight group and 317 patients were included in the overweight group. During the mean follow-up period of 48.8 months, 89 patients had disease recurrence and 131 deaths occurred. High BMI was significantly correlated with younger age, presence of diabetes, alcohol consumption, distal colon tumors, amount of lymph node harvested and pathological stage. No statistically significant correlation was found between high BMI and progression-free survival (PFS) or overall survival (OS) when the total group of patients was considered (P = 0.077 and P = 0.701, respectively). Cigarette-smoking patients had significantly shorter OS than patients who had never smoked (hazard ratio = 1.613, 95% confidence interval = 1.133 to 2.296; P = 0.008), and this difference in OS remained significant in multivariate analysis. Cigarette-smoking patients did not have significantly different PFS compared with patients who had never smoked.

There was no significant correlation between obesity and outcomes of patients with colorectal cancer. In addition, our findings support the claims that cigarette smoking may be partially responsible for the divergent mortality of patients with colorectal cancer.