Bowel cancer, or colorectal cancer is the third most common type of cancer worldwide. If the cancer develops enough, it can prove fatal, but if caught early enough, surgery can provide a solution. So, what causes bowel cancer? What does bowel cancer surgery entail? London-based colorectal surgeon Ms Sarah Mills explains the answers to these questions:
What causes bowel cancer?
Bowel cancers develop from polyps, which are benign growths arising from the lining of the bowel. If identified at an early stage they can be removed using a telescope called a colonoscope which is used to examine the lining of the bowel. This procedure is called a colonoscopy. If you are identified as having precancerous-type polyps, you can be entered into a program of regular surveillance with colonoscopy to allow future polyps to be removed before they become cancerous.
Polyps which are very large or appear suspicious are biopsied to see if they have become cancerous.
In some people there is an inherited chance of developing polyps or bowel cancer. Other risk factors include smoking, diet and environmental factors.
How is bowel cancer treated?
Once you have been diagnosed with bowel cancer the type of treatment you receive will depend on which part of the bowel is affected and how far the cancer has spread. Surgery is the most common option, though it may be combined with chemotherapy or radiotherapy. If it is spotted early enough the cancer can be stopped without it coming back.
Cancer in the colon
The exact type of bowel cancer surgery depends on the location of the cancer. Generally, the surgery involves removing the cancerous growth and the area around it. After the cancerous part of the colon is removed, the ends of the colon are joined back together. This can be done using keyhole surgery or open surgery. Lymph nodes close to this area also removed to stop the cancer from spreading.
Cancer in the rectum
Chemotherapy and radiotherapy may be used as a standard treatment, either before or after surgery, with an aim to reduce the size of the cancer before the operation or to reduce the risks of it returning post-operatively. If the tumour is small and discovered early enough it is possible to remove it through the anus, without the need to make a surgical incision in your abdomen. This is called transanal microsurgery (TAMIS). The surgeon inserts a special instrument into your anus to remove the tumour from the wall of the rectum using specialised forceps and a camera.
Total mesorectal excision (TME)
TME is the standard surgical technique for removing rectal cancers. It has proved successful at reducing rates of cancer recurrence. It involves the careful removal of the whole rectum as well as the fatty envelope around it, which contains the lymph nodes.
Depending upon the location of the bowel cancer, the operation is performed in the following way:
- Anterior resection:
The tumour is removed without affecting the anus. The colon is attached to the remaining part of the rectum and bowel movements return via the usual route, however, pattern of bowel function is usually altered to some extent. A temporary stoma may be necessary for a period of around twelve weeks after the operation, depending on the need for post-operative chemotherapy.
- Abdominoperineal (AP) resection:
An operation used to treat bowel cancer in the lower third of the rectum. The surgeon removes the affected part of the rectum, the anal sphincter muscles and the anus. Bowel movements cannot continue via the normal route and a permanent stoma is needed.