Impact of obesity on morbidity and oncologic outcomes after total mesorectal excision for mid and low rectal cancer

Background A recent meta-analysis showed that obesity increased the conversion rate and postoperative morbidity of rectal cancer surgery, but did not influence pathological results. However, this meta-analysis included patients with cancer of the upper rectum and had many biases. The aim of the present retrospective study was to investigate the impact of obesity, defined as a body mass index (BMI) >= 30 kg/m(2), on postoperative morbidity and short- and long-term oncologic outcomes of total mesorectal excision for mid and low rectal cancer in consecutive patients. Methods This study included all eligible patients who were operated on for mid and lower rectal cancer between 1999 and 2018 in our hospital. We compared 90-day postoperative morbidity and mortality, and short- and long-term oncologic outcomes between obese and non-obese patients. Results Three hundred and ninety patients [280 males, mean age 65.7 +/- 11.3 years, 59 obese individuals (15.1%)] were included. There was no difference in the 90-day mortality rate between obese and non-obese groups (p = 0.068). There was a difference in the overall 90-day morbidity rate between the obese and non-obese groups that disappeared after propensity score matching of the patients. There was no difference in short-term oncological parameters, with a median follow-up of 43 (20-84) months, and there were no significant differences in disease-free and overall survival between obese and non-obese patients (p = 0.42 and p = 0.11, respectively). Conclusions Obesity does not affect the 90-day morbidity rate, or short- and long-term oncologic results in patients operated on for mid and lower rectal cancer.