Background:~Obesity and underweight are associated with increased risk of postoperative morbidity in colorectal cancer patients undergoing surgery. There is a controversy regarding the effect of the two Body Mass Index (BMI) extremes on the oncological outcome of rectal cancer.~Objective:~The aim of this study was to evaluate the effect of BMI on short- and long-term oncological outcomes as well as postoperative complications in rectal cancer patients who received neoadjuvant chemoradiotherapy (nCRT) followed by surgery.~Setting:~Tertiary Cancer Center serving pediatric and adult patients in Jordan and the Middle East.~Patients:~The medical records of patients with stage II-III rectal cancer who received nCRT followed by surgery during 2006 to 2018 were retrospectively reviewed. The patients were subdivided according to their BMI into less than 20 kg/m2 defined as underweight; between 20 to 30 kg/m2 defined as normal range weight, above 30 kg/m2 defined as obese.~Main Outcome Measures:~Disease-Free Survival (DFS), Overall Survival, Pathological Complete Response (CR)
There is a controversy regarding the effect of the two Body Mass Index (BMI) extremes on the oncological outcome of rectal cancer.~The obesity paradox appears to exist in rectal cancer patients treated with nCRT and surgery, as it was associated with significantly higher rates of pathological complete response and R0 resection.~Underweight patients were at higher risk for anastomotic leak and R1 resection.