Bowel cancer

Category: Cancer

Topic: Bowel Cancer

Bowel cancer is a malignant growth that develops in the wall or lining of the colon. It begins when cells grow too quickly, forming a clump known as a polyp or adenoma. Polyps look like small spots on the bowel lining or like cherries on stalks. Most are benign (non-cancerous), but over several years, some can become cancerous. If left untreated, the cancer can spread to other areas of the body. If caught early, up to 90% of bowel cancers can be treated successfully.

Signs and Symptoms: 

Bowel cancer can develop without any obvious symptoms. However, symptoms of bowel cancer may include:

  • bleeding from the rectum (back passage
  • blood in bowel motions
  • changes to normal bowel habits which last for more than two weeks
  • unexplained tiredness or weakness (a symptom of anaemia)
  • ongoing abdominal pain or cramping

If you notice any of these symptoms, it does not mean you have bowel cancer, but it is very important that you discuss them with your doctor as soon as possible.

Both men and women are at risk of developing bowel cancer. The risk is greater if you:

  • are over 50 years of age
  • have a family history of bowel cancer or polyps
  • have a personal history of polyps or adenomas (pre-cancerous growths)
  • have a history of inflammatory bowel disease such as Crohn’s disease or chronic ulcerative colitis

If you are at an increased risk of developing bowel cancer, it does not necessarily mean you will develop the disease. It is recommended that you discuss your individual risk with your doctor.


While no cancer is completely preventable, you can lower your risk of bowel cancer by:

  • being physically active
  • limiting alcohol intake
  • avoiding smoking
  • eating a healthy and balanced diet
  • participating in bowel cancer screening

It is recommended that all people aged 50 years and over with no symptoms be screened for bowel cancer every 2 years.

Screening and other tests

Screening involves testing for bowel cancer in people who do not have any obvious symptoms of the disease. The aim is to find any polyps or cancer early when it is easier to treat and cure. Bowel cancer can develop without any early warning signs. The cancer can grow on the inside wall of the bowel for several years before spreading to other parts of the body. Often very small amounts of blood leak from these growths and pass into the bowel motion before any symptoms are noticed.

A test called a Faecal Occult Blood Test (FOBT) can detect tiny amounts of blood, often released from bowel cancers or pre-cancerous growths (polyps or adenomas) into the bowel motion. Although no screening test is 100% accurate, the FOBT is currently the most well researched screening test for bowel cancer. If you develop any of the symptoms of bowel cancer or discover a family history of bowel cancer you should contact your doctor as soon as possible to discuss the type of testing that is most suitable for you.

Screening and other tests:

  • FOBT: A simple test that looks for tiny amounts of blood in the bowel motion, but not for bowel cancer itself. It involves taking two small samples from bowel motions. Samples are then sent to a laboratory for testing. If blood is found in a FOBT (positive result), further tests such as a colonoscopy are needed to determine the cause of the bleeding. The National Bowel Cancer Screening Program sends a free screening kit to eligible people.
  • Colonoscopy: Used to investigate bowel symptoms and as a follow-up for positive FOBTs. A long, thin, lighted tube is inserted through the anus to allow a visual examination of the colon. If a polyp or early bowel cancer is detected, the doctor can remove it during the examination.
  • Flexible sigmoidoscopy: Only explores the lower part of the bowel, where two thirds of all bowel cancers occur. A tube containing a small flexible video system is inserted into the lower part of the bowel that transmits images onto a video-like screen. If pre-cancerous polyps are detected during a flexible sigmoidoscopy, a full examination by colonoscopy is usually required.
  • CT Colonography/virtual colonoscopy: Requires the same diet and bowel preparation as a colonoscopy. It is mainly used for people who are unable to undergo a colonoscopy. CT colonography is essentially a CT scan of the entire abdomen including the bowel.
  • Double-Contrast Barium Enema (DCBE): This procedure also involves bowel preparation similar to colonoscopy. Fluid-like barium is then introduced into the bowel and a scan is taken of the bowel.
Health outcome: 

Early detection through a screening program offers the best hope of reducing the number of Australians who die each year from bowel cancer. Bowel cancer is one of the most curable types of cancer if found early.

If you participate in screening and do a FOBT every two years, you can reduce your risk of developing bowel cancer