Surgery

Surgical removal of a tumor is the cornerstone of curative therapy for localized rectal cancer. In addition to removing the rectal tumor, removing the fat and lymph nodes in the area of a rectal tumor is also necessary to minimize the chance that any cancer cells might be left behind.

However, because the rectum is in the pelvis and is close to the anal sphincter (the muscle that controls the ability to hold stool in the rectum), rectal surgery can be difficult. With more deeply invading tumors and when the lymph nodes are involved, chemotherapy and radiation therapy are usually included in the treatment course to increase the chance that all microscopic cancer cells are removed or killed.

Four types of surgeries are possible, depending on the location of the tumor in relation to the anus.

• Transanal excision: If the tumor is small, located close to the anus, and confined only to the mucosa (innermost layer), then performing a transanal excision, where the tumor is removed through the anus, may be possible. No lymph nodes are removed with this procedure. No incisions are made in the skin.
  
  
• Mesorectal surgery: This surgical procedure involves the careful dissection of the tumor from the healthy tissue. Mesorectal surgery is being performed mostly in Europe.
  
  
• Low anterior resection (LAR): When the cancer is in the upper part of the rectum, then a low anterior resection is performed. This surgical procedure requires an abdominal incision, and the lymph nodes are typically removed along with the segment of the rectum containing the tumor. The two ends of the colon and rectum that are left behind can be joined, and normal bowel function can resume after surgery.
  
  
• Abdominoperineal resection (APR): If the tumor is located close to the anus (usually within 5 cm), performing an abdominoperineal resection and removing the anal sphincter may be necessary. Lymph nodes are also removed during this procedure. With an abdominoperineal resection, a colostomy is necessary. A colostomy is an opening of the colon to the front of the abdomen, where feces are eliminated into a bag.