Rectal cancer surgery is most often the main treatment for rectal cancer, although radiation therapy and chemotherapy may be used either before or after surgery. The goal of rectal cancer surgery is to remove or destroy the rectal cancer. This can be accomplished through a few different surgical methods.
Two such procedures are a polypectomy and local excision. Both are performed during a colonoscopy, and require no surgical opening in the skin of the abdomen. A polypectomy is the removal of a polyp; a local excision is the removal of cancerous cells and the surrounding tissue.
A local transanal resection (also called a full thickness resection) is also performed during a colonoscopy. In this procedure, the doctor cuts through all layers of the rectum to remove cancer as well as some surrounding normal rectal tissue, and then closes the hole in the rectal wall. This procedure is usually done for very early-stage cancers. For early-stage cancers too high in the rectum to be reached through transanal resection, transanal endoscopic microsurgery may be an option. A specially designed magnifying scope is inserted through the anus into the rectum, allowing the surgeon to perform a resection.
A low anterior resection may be used for some stage I rectal cancers and most stage II or stage III cancers in the upper third of the rectum, close to where it connects with the colon. In this surgery, the part of the rectum containing the tumor is removed, and then the colon is attached to the remaining part of the rectum, allowing patients to move their bowels normally. This procedure is done through an incision in the abdomen. If radiation therapy and chemotherapy have been given beforehand, a temporary ileostomy (in which the last part of the small intestine is brought out through a hole in the abdominal wall to enable the patient to pass waste) may be formed. This can usually be reversed in about eight weeks.
Most stage II and stage III rectal cancers in the middle and lower third of the rectum require a procedure called a proctectomy. Here, the entire rectum (along with nearby lymph nodes) is removed, and the colon is connected to the anus. In some cases, a colo-anal anastomosis is performed: a small pouch is formed by doubling back a small segment of the colon or by enlarging a segment. This pouch functions as a reservoir for fecal matter, like the rectum did previously.
Other cancers in the lower third of the rectum, particularly cancers growing into the sphincter muscle, need a procedure called an abdominoperineal (AP) resection. In this resection and colostomy, the anus and surrounding tissues (including the sphincter) are removed. The patient will then need a permanent colostomy to allow stool to leave the body.
Finally, there is pelvic exenteration. For rectal cancers growing into nearby organs, this extensive operation, in which the rectum, bladder, and prostate (in men) or uterus (in women) are removed if the cancers have spread to these organs, may be necessary. Patients who receive this operation will require a colostomy to pass stool and a urostomy to pass urine.