Polyps and bowel cancer treatment
Bowel cancers arise from the lining of the large intestine, also known as the colon. Tumours may also arise from the lining of the very last part of the colon, called the rectum.
Unfortunately, most colorectal cancers are "silent" tumours. They grow slowly and often do not produce symptoms until they reach a large size. Fortunately, bowel cancer is curable, if detected early.
How does bowel cancer develop?
Bowel cancer usually begins as a polyp. The word "polyp" is a nonspecific term to describe a bump on the surface of the colon. Polyps can also be bumps of normal colorectal lining which do not increase the risk of colorectal cancer.
The two most common types of polyps found in the large intestine include:
- Hyperplastic polyps. Usually small, and on the left side of the colon, polyps that do not carry a risk of developing into cancer. However, large hyperplastic polyps, especially on the right side of the colon, are of concern and should be completely removed.
- Adenomas or adenomatous polyps. Benign polyps, which, if left alone, could turn into colon cancer.
Although most colorectal polyps never become cancer, virtually all colon and rectal cancers start from these benign growths.
Polyps and colon cancer develop when there are mutations or errors in the genetic code that controls the growth and repair of the cells lining the colon. People may inherit diseases in which the risk of colon polyps and cancer is very high.
What are the risk factors for bowel cancer?
While anyone can get bowel cancer, it is most common among people over the age of 50. Risk factors for colorectal cancer include:
What are the symptoms of bowel cancer?
The earliest sign of colon cancer may be bleeding. Often tumours bleed only small amounts intermittently, and evidence of the blood is found only during chemical testing of the stool. This is called occult bleeding, meaning it is not always visible to the naked eye. When tumours have grown to a large size they may cause a change in the frequency or the diameter of the stool.
Common symptoms of colorectal cancer include:
Bowel cancer screening
Unfortunately, colorectal cancer may strike without symptoms. For this reason, it is very important to take up the invitation to be screened even if you have no symptoms.
In England, Wales and Northern Ireland men and women aged 60 – 74 are invited to be screened every two years. In Scotland, the screening is every two years between 50 to 74 years of age.
Those with a personal or family history of colorectal polyps or cancer or inflammatory bowel disease, or at high-risk of bowel cancer, will be advised how often they should undergo screening. Screening is usually with flexible sigmoidoscopy and/or colonoscopy.
There are a number of tests your doctor can perform to diagnose colorectal cancer. These tests include:
- Sigmoidoscopy. This is a procedure used to examine the very last part of the colon (sigmoid colon and rectum). This test can detect polyps, tumours, and other changes in the sigmoid colon and rectum. During this examination, a biopsy (tissue sample) can also be taken for testing.
- Colonoscopy. A colonoscopy examines the entire colon and rectum. During this procedure, a biopsy may be taken.
- Colon X-rays. Also known as a barium enema or lower GI series, this test provides an outline of the colon lining as well as detecting polyps, tumours, and changes in the colon and rectum.
- Colonography. This is an X-ray done of the entire colon using a CT (computed tomography) scanner. This test takes less time and is less invasive than a colonoscopy. It can detect polyps usually greater than 1cm. However, if a polyp is detected, a standard colonoscopy needs to be performed.