This prospective study was approved by the Institutional Review Board of Severance Hospital. Patients were enrolled between September 2011 and December 2013. Inclusion criteria were as follows: age >20 years; ECOG performance status ≥2; diagnosis of rectal adenocarcinoma via endoscopic biopsy, stage T3 or T4, or with clinically enlarged regional lymph nodes identified by CT or rectal magnetic resonance imaging (MRI) regardless of T stage; and having completed preoperative CRT followed by TME with curative intent. Exclusion criteria were as follows: stage IV disease; familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer; benign disease; tumor located more than 10.0 cm from the anal verge; previous or concurrent malignant disease; and patient refusal. Of 122 consecutive patients originally recruited, 12 patients were initially excluded for the analysis: 8 with a mucinous component by preoperative rectal MRI, 2 with incomplete MRI protocols, 1 with stent insertion for an obstructive lesion, and 1 with incomplete data. The remaining 110 patients who fulfilled the inclusion criteria were finally included (Fig. 1).