Bowel cancer, also known as colorectal cancer, is a cancer of the lining of the colon or rectum. It is the number two cancer-killer in Australia with one person dying every two hours - and more than from breast or prostate cancer.

Cancer of the large bowel (colon and rectum) is the most commonly diagnosed internal cancer in Australia that affects both men and women. Approximately one in 12 Australians are diagnosed before the age of 85.  Cancer of the small bowel (small intestine) is quite uncommon.

The large bowel is a muscular tube one to two metres in length. The rectum is the last 15cm of the large intestine, and this leads to the anal canal, which is around three centimetres long and leads to the outside of the body.

Bowel cancer is a malignant tumour, which generally begins in the lining of the bowel.

digestive system diagram v3

Untreated, it will increase in size, protruding into the bowel wall and may cause blockage or can ulcerate, leading to blood loss and anaemia.  It can also spread to other organs.

How does bowel cancer develop?

Most bowel cancers start as wart-like growths, called polyps, which grow on the wall of the bowel. Polyps are usually harmless (benign) but can become cancerous over time.

Polyps are very common as we get older and while there are different types, most do not become cancerous. The polyps associated with bowel cancer are termed ‘adenomatous polyps’ or simply adenomas.  Patients who are found to have adenomas are considered at risk of developing bowel cancer.

Early detection and removal of pre-cancerous polyps prevents the development of bowel cancer.

If untreated, bowel cancer can spread (or metastasise) deeper into the wall of the bowel, or invade nearby organs.  From there, it can spread through the body via the blood stream and the lymph system.

Lymph nodes are small, oval-shaped organs that are found throughout the body. They are an important part of the immune system, and help your body recognize and fight germs, infections, and other foreign substances.

Over time, bowel cancer can spread to other organs of the body, such as the liver or lungs, via the lymph nodes.   In most cases this happens slowly, and can be in the bowel for months or years before it spreads.

When bowel cancer is diagnosed early, there is an excellent chance of being completely cured.  If the disease is widespread throughout the body, it may be impossible to cure, but the disease may still be controllable.

Bowel cancer facts

  • Australia has one of the highest rates of bowel cancer in the world.
  • Over 14,000 men and women Australians are diagnosed each year.
  • In Victoria alone, over 1,300 die annually – more than 3 times the states road toll.
  • Bowel cancer affects men and women of all ages, almost equally.
  • Risk increases with age.
  • 1 in 12 Australians will develop bowel cancer in their lifetime.
  • While 90% of bowel cancers occur in those 50 and over - around 1,000 younger Australians are diagnosed each year.
  • Screening every 1-2 years can reduce the risk of dying from bowel cancer by up to 33%.