Australian Government Department of Health
National Bowel Cancer Screening Program
Photos of Older Australians

Bowel Cancer - the facts

Bowel cancer is a major public health problem in Australia. Around 80 Australians die each week from the disease. It is one of the most commonly occurring internal cancer and the second most common cause of cancer related death, after lung cancer.

About the Bowel

The bowel is part of the food digestive system. It connects the stomach to the anus, where waste materials (called a bowel motion or faeces) are passed out of the body. The function of the bowel is to finish digesting food by absorbing water and nutrients.

The bowel has three parts:
  • the small bowel - which mainly absorbs nutrients from broken-down food;
  • the colon - which mainly absorbs water; and
  • the rectum - which stores waste material until it is passed from the body through the anus.
The colon and rectum together are known as the large bowel. Bowel cancer usually affects the large bowel. Cancer of the large bowel is also known as colorectal cancer. Cancer of the small bowel is rare.
An illustration of the human bowel, as described in the text under the heading ‘About Your Bowel’
Illustration above adapted from original illustration, courtesy of The Cancer Council Victoria.

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What is bowel cancer?

Bowel cancer is a malignant growth that develops most commonly inside the large bowel. Most bowel cancers develop from tiny growths inside the colon or rectum called polyps, which look like small spots on the bowel lining or like cherries on stalks. Not all polyps become cancerous. If polyps are removed, the risk of bowel cancer is reduced.

The beginnings of bowel cancer
An illustration showing how bowel cancer begins to develop, as described in the text under the heading ‘What is bowel cancer?’
Illustration above adapted from original illustration, courtesy of The Cancer Council Victoria.

How common is bowel cancer?

Bowel cancer is one of Australia’s most common cancers, especially for people over 50. In 2008 approximately 14,225 new cases of bowel cancer were diagnosed. It is also a major cause of cancer deaths with around 80 Australians dying from bowel cancer each week. During 2010, lung, bowel, prostate, breast and pancreatic cancer were the most common causes of cancer related death in Australia.

Graphical Presentation of Number of Deaths in Men and Women due to different types of Cancer D

4,934 deaths in Men due to Lung Cancer
2,205 deaths in Men due to Bowel Cancer
3,235 deaths in Men due to Prostate Cancer

3,165 deaths in Women due to Lung Cancer
1,777 deaths in Women due to Bowel Cancer
2,840 deaths in Women due to Breast Cancer

Source: Australian Institute of Health and Welfare & Australasian Association of Cancer Registries 2012. Cancer in Australia - an overview 2012. Cancer series no. 74 Cat. No. CAN 70. Canberra: AIHW

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What causes bowel cancer?

It is difficult to give one reason. However, for most people it is their age and their diet that contribute to the development of bowel cancer.

How does bowel cancer develop?

The development of bowel cancer generally takes many years. It starts on the inside wall of the bowel and can grow there for several years before spreading to other parts of the body. Often very small amounts of blood, not visible to the naked eye, are leaked from these cancers long before any symptoms develop. This blood is then passed into the faeces.

What are the symptoms of bowel cancer?

Bowel cancer can develop with few, if any, early warning symptoms. Symptoms of bowel cancer can include: bleeding from the rectum or any sign of blood after a bowel motion; a recent and persistent change in bowel habit, for example looser bowel motions, severe constipation and/or needing to go to the toilet more than usual; unexplained tiredness (a symptom of anaemia); and abdominal pain.

People who have symptoms should see their doctor, even if no blood is detected in their FOBT.

If a person has symptoms that could indicate bowel cancer, what should they do?

People with symptoms of bowel cancer should consult their doctor for clinical diagnosis and advice as soon as possible.

If a person has rectal bleeding, do they have bowel cancer?

Not necessarily. There are many causes of rectal bleeding. However, symptoms of bowel cancer, including rectal bleeding should be discussed with a doctor as soon as possible so that the cause of bleeding can be found.

Can bowel cancer be cured?

Bowel cancer can be treated successfully if detected in its early stages, however, fewer than 40% of bowel cancers are detected early. International randomised control trials have demonstrated that population screening for bowel cancer, using FOBTs, can reduce deaths from bowel cancer by 15-33%.

Can bowel cancer be prevented?

While no cancer is completely preventable, it is believed that eating a healthy diet and exercising regularly could prevent 66 to 75% of bowel cancer cases. It is never too late to make changes to your diet and lifestyle. More information on a healthy diet can be obtained from your doctor. The following publications: Dietary Guidelines for Australian Adults - Book and Food for Health - Dietary Guidelines for Australian Adults - Pamphlet provide information on a healthy diet.

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Who is at risk of bowel cancer?

Both men and women are at risk of developing bowel cancer. In Australia, the lifetime risk of developing bowel cancer before the age of 75 years is around 1 in 19 for men and 1 in 28 for women. This is one of the highest rates of bowel cancer in the world.

The risk is greater for people who:
  • are aged 50 years and over - risk increases with age;
  • have a significant family history of bowel cancer or polyps;
  • have had an inflammatory bowel disease such as Crohn’s disease or ulcerative colitis; or
  • have previously had special types of polyps, called adenomas, in the bowel.
People at above average risk of bowel cancer should talk to their doctor about relevant screening options.

A significant family history of bowel cancer

A person is considered to have a significant family history of bowel cancer if a close relative (parent, brother, sister or child) developed bowel cancer at a young age (under 55 years) or if more than one relative on the same side of your family has had bowel cancer.

More than 75% of people who develop bowel cancer do not have a family history of bowel cancer. People who think they have a family history of bowel cancer should talk to their doctor about their risk of getting the disease.

Page currency, Latest update: 18 November, 2013