Transanal Endoscopic Rectosigmoid Resection with Laparoscopic Assistance was developed at Massachusetts General Hospital and performed successfully to remove cancer of the lower rectum. Based on the outcomes, the research doctors believe that this investigational surgery may be as safe and effective as standard laparoscopic or open surgery performed to remove rectal cancer, may facilitate the operation and reduce the size of the abdominal incisions. In this research study, the investigators are looking to see if this investigational procedure is a safe and effective approach to remove rectal cancer of the mid and lower rectum.

Subjects will have their rectal cancer removed using a technique combining surgery through the anus and standard laparoscopy. At the end of the procedure, the rectum will be removed though the anus, the bowel will be re-connected to the anus, and a temporary diverting stoma will be created, which is standard of care following surgery for this type of cancer.

Inclusion Criteria:

• Biopsy-proven adenocarcinoma of the rectum
• Eligible to undergo standard open or laparoscopic low anterior resection with a temporary diverting stoma
• Node negative (N0), T1 (high risk features), T2 and T3 rectal cancer on pelvic MRI
• Closest distance between tumor edge and mesorectal fascia 5mm or more based on pelvic MRI
• Rectal cancer located 4-12 cm from the anal verge
• ECOG performance status 2 or less

Exclusion Criteria:

• Metastasis
• Obstructing rectal cancer
• Synchronous colon cancer
• T3 rectal cancer not treated preoperatively with full-course chemoradiation
• Pregnant or breast-feeding
• Receiving any other study agents
• Fecal incontinence
• History of prior colorectal cancer
• History of inflammatory bowel disease
• History of pelvic radiation
• Prior pelvic surgery or multiple abdominal procedures
• BMI > 30
• Large uterine fibroids
• Uncontrolled intercurrent illness
• Other malignancies diagnosed within the previous year, except basal cell cancer