Proximally Extended Resection for Rectal Cancer After Neoadjuvant Chemoradiotherapy

Inclusion Criteria: * Age: 18-75 years old * ECOG performance status: 0-2 * Histologically confirmed adenocarcinoma of the rectum * Distal border of the tumor located ≤ 12 cm from the anal verge * Primary stage T3-4 or any node-positive disease * Undergoing long-course 5-fluorouracil based neoadjuvant chemoradiotherapy * Conventional fractionated radiotherapy of at least 45 Gy * Resectable disease after neoadjuvant chemoradiotherapy * No evidence of distant metastasis * Amenable to sphincter-preserving surgery * Tolerable to general anesthesia * Provision of written informed consent Exclusion Criteria: * Prior or concurrent malignancies within the past 5 years except for effectively treated squamous cell or basal cell skin cancer, melanoma in situ, or carcinoma in situ of the cervix * Synchronous colon cancer * History of colorectal resection except appendectomy * Acute intestinal obstruction or perforation * Multiple visceral resection * Abdominoperineal resection * American Society of Anesthesiologists (ASA) class Ⅳ or Ⅴ * Pregnant or nursing, fertile patients do not use effective contraception * Serious cardiovascular disease, uncontrolled infections, or other serious uncontrolled concomitant disease * Psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol and follow-up schedule