Overweight but not obesity is associated with decreased survival in rectal cancer.

Objective: To analyse the influence of overweight and obesity in disease-specific survival (DSS) in rectal cancers at stages I-III in a population with high prevalence of overweight/obesity.

Methods: The population (N = 304) consisted of Mexican patients with stage I-III rectal cancer during the period between 2009 and 2015. Patients were divided based on their body mass index (BMI) into normal weight 18-25 kg/m2, overweight 25-29 kg/m2, and obesity BMI > 30 kg/m2 groups. Comparison of clinicopathologic features and survival analysis were performed.

Results: The median age was 58 years (interquartile range [IQR] 50-65) and the mean BMI was 26.03 ±4.06 kg/m2. Patients in the obesity and overweight groups received a lower proportion of preoperative treatment and had a higher proportion of patients in stage II. Overweight patients had a lower baseline neutrophil/lymphocyte ratio and lower survival rate than patients with normal weight and with obesity (mean survival of 69.5 months vs. 81.15 months and 86.4 months, respectively). The estimated five-year DSS was 51% for the overweight group, 81% for the normal group, and 82% for the obesity group (p = 0.026).

Conclusions: Patients with stage I-III rectal cancer in the overweight group showed a lower DSS compared to groups with normal weight and with obesity, with the last two being similar.