Colon cancer screening

Colon cancer is a common cause of death in Australia, with a lifetime risk of about 1 in 19 (over 5%) for men and 1 in 28 for women. The risk increases sharply over the age of 50. Around 80 Australians die each week from bowel cancer, but if found early it is one of the most curable types of cancer. Bowel cancer develops when cells in the bowel lining grow too quickly, forming a clump known as a polyp or an adenoma. Studies have shown that screening tests can prevent colon cancer.

If you have a family history of colon cancer then you need to discuss this with your doctor as to when you should be tested.

The risks of colon cancer includes:

Age over 50

Family history

If you have inflammatory bowel disease

If you had previous polyps

Some symptoms of bowel cancer may include:

Change in bowel habits such as constipation or diarrhoea

Blood in the stools

Abdominal pain

Loss of appetite

Unexplained weight loss

Bloating

There may be no symptoms before the cancer gets diagnosed.

Common screening tests for colon cancer may include:

Stool test for blood (faecal occult blood test). Advantages of this test - This test does not involve cleaning out the colon or having any procedures. Drawbacks to this test – Stool tests are less likely to find polyps than other screening tests. These tests also often come up abnormal even in people who do not have cancer. If a stool test shows something abnormal, doctors usually follow up with a colonoscopy.

Faecal occult blood test (FOBT)

Colonoscopy allows the doctor to see directly inside the entire colon. Before you can have a colonoscopy, you must clean out your colon. You do this by drinking a special liquid that causes watery diarrhoea. On the day of the test, you get medicine to help you relax. Then a doctor puts a thin tube into your anus and advances it into your colon. The tube has a camera attached to it, so the doctor can see inside your colon. The tube also has tools on the end, so the doctor can remove pieces of tissue, or polyps if they are there. After polyps or pieces of tissue are removed, they are sent to a lab to be checked for cancer.

Advantages of this test – Colonoscopy finds most small polyps and almost all large polyps and cancers. If found, polyps can be removed right away.

Drawbacks to this test – Colonoscopy has more risks than the other screening tests. In 1 in 1,000 people, it can cause bleeding or tear the inside of the colon. Cleaning out the bowel beforehand can be unpleasant. Plus, people usually cannot work or even drive themselves home the day of the test, because of the relaxation medicine they must take during the test.

Other tests include a flexible sigmoidoscopy (limited examination of the colon) or a CT colonography (imaging of the colon), however these tests have significant limitations.