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.

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)

Inclusion Criteria:

• Patients who underwent rectal surgery at King Hussein Cancer Center (KHCC) from 2006 to 2018 were identified. Those with locally advanced rectal cancer (stages II and III) who underwent nCRT followed by surgery with curative intent were included.

Exclusion Criteria:

• Patients with early rectal cancer (stage I) who did not require nCRT and those who underwent rectal surgery as part of a staged or simultaneous approach for metastatic disease (stage IV) were excluded.

294 patients included in the study