What is the cause of bowel cancer?
The exact cause is unknown, but most cases begin as polyps, which are small growths inside the (large intestine or bowel) colon or rectum. Polyps are very common, and the majority of them do not turn into cancer. Most polyps are easily found with fairly simple screening tests and can be removed at the same time.
You are more likely to get bowel cancer if you eat a high-fat diet, smoke, or have a history of this type of cancer in your family. However, 80% of people who get bowel cancer do not have any close relatives with the illness.
What is a polyp?
Polyps vary in their shape, size and location within the large bowel. They may be single or multiple. A typical polyp has the appearance of a cherry with a short stalk (or pedicle). Most polyps measure up to about one centimetre in diameter. Some have no stalk and are flat, spreading over the lining surface of the bowel.
At what age does bowel cancer occur?
It is usual for bowel cancer to occur around 50 years of age; with an increasing risk in later years.
If I have a relative with bowel cancer does that increase my risk?
One close relative such as a mother, father, sister, brother or child, increases the risk of bowel cancer two to three times. Two close relatives increases the risk eight times.
Who is most at risk of getting bowel cancer?
- People who have already had bowel cancer or polyps.
- People with one or more close relatives (mother, father, brother, sister or child) who have had polyps or bowel cancer.
- People who have had extensive, long-standing inflammatory bowel disease (Crohn’s disease or ulcerative colitis).
Is it catching?
No, bowel cancer is not catching. It is true that people who have a family history or bowel cancer are more likely to get it than people who don’t, but that doesn’t mean you can pass it on to anybody else. Nor does it mean you can catch it off anybody.
Is it possible to have blood in your stool, but not have bowel cancer?
Yes, it is quite common to have blood in your stool but not have colon cancer. Rectal bleeding or blood in or on the stool is never normal and should not be ignored. You should see your doctor immediately.
What are the symptoms of early bowel cancer?
In the early stages, when bowel cancer can be more easily cured, there are few, if any, symptoms. After that, these are the symptoms to look for:
- Bleeding from the bowel. While this is the most important symptom, it does not always mean that bowel cancer is present.
- Abdominal symptoms such as pain, bloating, weight loss or mucous in bowel motions.
- Change in bowel habit, ranging from constipation to persistent diarrhoea.
- Low iron levels, which can cause anaemia and tiredness.
I have noticed a change in my bowel movements - from constipation to going a couple of times a day. Could this be an indication of irritable bowel syndrome or possibly cancer?
Irritable bowel syndrome is a common disorder that leads to cramps, bloating and changes in bowel habits, including constipation. The chances are it is not cancer. However, the symptoms of bowel cancer and irritable bowel syndrome are similar, so your doctor will need to do tests to diagnose the problem.
Is bowel cancer preventable?
You can help prevent bowel cancer with regular testing. Bowel cancer almost always starts with a polyp, a small growth on the lining of the colon or rectum. Finding and removing polyps before they become cancerous will stop bowel cancer before it starts.
What types of tests are used to detect bowel cancer?
It is possible to have bowel cancer and not have any symptoms, which is why regular screening is vital. Screening can find polyps, which when removed prevent bowel cancer from developing. Even if cancer is found, regular screening means it is likely to be found in the early stages which greatly improves the chances of successful treatment. There are a number of screening methods available.
- Faecal Occult Blood Test
A simple test that can be done at home. The test detects tiny amounts of blood, often released from bowel cancers or their precursors (polyps or adenomas) into the stool. FOBT can’t actually tell if you have cancer, but is used to identify people who require further testing. Not all polyps are detected by FOBT & some small cancers can occasionally be missed, which reduces its effectiveness as an ideal screening method.
- Rectal Examination
The simplest form of internal rectal examination in which a doctor simply feels for any irregularities in the lowest part of the bowel.
- Flexible Sigmoidoscopy
A flexible tube is used to examine the rectum and lower colon for polyps & cancer. It views about one third of the colon.
- Colonoscopy
A long, flexible tube, with a tiny lens on the tip, is inserted into the rectum then guided around the colon. During colonoscopy, the doctor can remove polyps and take some tissue (a biopsy) to test for cancer. Colonoscopy is the most effective screening method, as it finds polyps and removes them.
- Virtual colonoscopy
This is a type of CT scan that gives a picture of the colon. If a virtual colonoscopy shows a problem, then a colonoscopy will be needed to enable removal of growths. Whilst less invasive than colonoscopy, a Virtual Colonoscopy does not detect all polyps, which reduces its effectiveness as a screening method.
- Barium Enema
Barium, a white liquid, is delivered into the rectum using a small tube. Air is used to make sure the barium finds its way into creases in the bowel & shows up clearly when x-rays are taken. This screening method detects the larger bowel cancers, but can easily miss polyps and even small cancers, making it less accurate than a colonoscopy.
How is bowel cancer diagnosed?
If your doctor thinks you may have bowel cancer, you will need a colonoscopy to allow the doctor see the inside of your colon. During this test your doctor will remove polyps or take tissue samples from any areas that don't look normal. Another doctor, called a pathologist, will look at the tissue under a microscope to see if it contains cancer.
How is it treated?
Treatment depends on where the tumour is and how far it has grown into the wall of the colon. In most cases, surgery is used to remove the cancer. Sometimes radiation or chemotherapy is also used. These treatments have side effects, which are usually manageable with drugs or home care.
How can I prevent bowel cancer?
You can prevent bowel cancer with regular screening from the age of 50. The polyps generally begin to occur in your 40’s and bowel cancer in your 60’s (although both occasionally occur at younger ages).
You can also reduce your risk by;
- Eating a healthy diet, including plenty of vegetables and fruit and a small amount of animal fat.
- Maintaining a healthy body weight
- Not smoking
- Reducing your intake of alcohol
- Exercising regularly
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