Surgery is the most important treatment for rectal cancers. The presently accepted oncological concept is total mesorectal excision (TME), which is removal of the rectum along with the fat surrounding it and the blood vessels supplying it. This would include all the lymph nodes draining rectum. As opposed to blunt dissection of rectum, TME has been shown to reduce the local recurrence significantly. The TME specimen should have specific macroscopic characters. The best measure of the quality is the clear circumferential and cut margins, and the number of harvested lymph nodes (>12).
Depending on the location of the tumor within the rectum three types of surgeries can be performed:
1. Abdomino-Perineal Resection (APR)- This procedure is performed when it is not feasible to preserve anal sphincter due to involvement or being very close to tumor. This involves resection of sigmoid colon along with rectum and anal canal. A permanent colostomy is made.
2. Anterior Resection (AR)- This is the surgery offered to cancers above the peritoneal reflection of rectum. Colon along with upper portion of rectum are resected Remnant of colon is anastomosed to the remnant of rectum.
3. Low Anterior Resection (LAR)- This surgery is performed when the disease involves rectum bellow the peritoneal reflection of rectum. This can per performed provided there is at least 1 cm clear margin.
4. Ultra Low Anterior Resection- This procedure can be performed when the disease reaches upto 2 cm above the dentate line. In this procedure entire rectum is removed with preservation of sphincter. This coloanal anastomosis may be considered if the margins are too close.