Surgery for Colorectal Cancer
Surgery is the mainstay of treatment for colon cancer and is very effective (80-90% cure rates) for treating early tumors that are confined to the intestine. Colon cancer starts off from the inner lining of the colon wall – known as the mucosa and spreads by direct invasion through the different layers of the bowel wall. Having grown into the wall of the colon, the tumor can then spread to lymph nodes, through the blood stream or by seeding through the abdominal cavity. If the cancer has spread to other organs, the chance of cure is much reduced.
In performing surgery for colorectal cancer, the surgeon has several goals in mind. Firstly, he must remove the tumor completely with clear margins, so that no tumor is accidentally left behind to grow back. The lymph nodes that drain the tumor must also be removed as they are the most likely site of tumor spread, and this tissue is then sent for histologic examination under a microscope to determine if the lymph nodes are involved. This information is necessary for deciding if chemotherapy or radiotherapy is necessary in the postoperative period.
The third consideration the surgeon has is to restore bowel continuity and function. In most instances, it will be possible to remove the tumor and anastomose (join back) the intestine by means of either sutures or special stapling guns. In the rare instance where the tumor is invading the anal muscles, the surgeon may find it necessary to make a permanent colostomy.
Laparoscopic Colorectal Surgery:
Laparoscopic surgery (or minimally invasive surgery) is a new and exciting innovation in the treatment of colorectal cancer. The same operation is performed as in conventional open colorectal surgery, but the trauma induced is minimized. The procedure is performed instead by inserting special instruments and a camera system through small 5-10 mm incisions instead of making a large cut across the abdomen.
For the full article on Laparoscopic Colorectal Surgery, please click here.
Further treatment with chemotherapy or radiotherapy is only necessary if there is a high risk of tumor recurrence. Chemotherapy is essentially a selective poison that destroys tumor cells that may have spread to other organs. In colon cancer, chemotherapy is used to treat Stage 3 disease, where lymph nodes are involved by cancer and the risk of dying from the cancer is about 60% at 5 years. Addition of chemotherapy in this situation improves the chances of survival to about 50%. Chemotherapy has not been shown to significantly affect survival if the lymph nodes are not involved by the cancer.
There are different chemotherapy regimes, each with different side effects and some are more effective than others. Your doctor will assess you and discuss with you the risks and benefits of each treatment so you can make an informed decision.
Radiotherapy is mostly used for treatment of rectal cancer – where it has been shown to reduce the risk of local recurrence. The difficulty in rectal cancer is that the tumor is located within the limited confines of the pelvis, which makes surgical removal of the tumor with clear margins a technical challenge. Radiotherapy reduces the local recurrence rates following surgery by 50%.
Radiotherapy can be given either preoperatively or postoperatively. In general, it is preferable to give radiotherapy preoperatively as there are less side effects and the radiation can cause tumor shrinkage and make surgery for sphincter preservation easier. Chemotherapy can be added to radiotherapy to increase it’s effectiveness. The side effects of radiotherapy are poor wound healing, possible damage to adjacent loops of intestine and adhesions.