Bowel Cancer

Bowel cancer, also known as colorectal cancer, refers to cancer which develops in any part of the large bowel (colon) or rectum.

Last modified: November 16, 2021

Quick facts about bowel cancerQuick facts

  • Most bowel cancer starts with the development of growths, called polyps, on the inner lining of the intestine
  • Bowel cancer is the second most common cancer in both men and women in Australia and is more common in people over the age of 50

Types of bowel cancerTypes of bowel cancer

Bowel cancer refers to both colon cancer and rectal cancer. 

Colon cancer

Colon cancer originates in the large intestine, also known as the colon. In many cases, early signs of colon cancer include non-cancerous polyps in the colon. 

Rectal cancer

Rectal cancer develops in the end of the large intestine, known as the rectum. Like cancer found in the large intestine, it can begin with the formation of non-cancerous polyps.

Signs and symptoms of bowel cancerSigns and symptoms

As signs and symptoms for bowel cancer can be similar to other common conditions such as haemorrhoids, it’s important to see your GP or healthcare professional if you experience any of the symptoms below. Discussing anything concerning with your doctor as soon as possible can help give you peace of mind and offer the best chance of successful treatment if you receive a bowel cancer diagnosis.

Symptoms may include:

  • Sudden changes in bowel movements, like diarrhoea, constipation, narrower stools, or stools that contain mucus

  • Unexplained weight loss or loss of appetite

  • Bright red or dark blood in your stool or on the toilet tissue

  • Pain in your stomach with or without swelling

  • Constant gas or bloating in the bowel or rectum

  • A lump or pain around the anus

  • Unexplained anaemia (low iron) which can cause tiredness and breathlessness

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Stages of bowel cancerStages

The TNM system is used to stage bowel cancer, and it helps doctors understand what your cancer looks like. The TNM stands for:

  • Tumour – The degree to which the tumour has affected other tissue, for example has it grown outside the wall of the rectum or colon
  • Node – Is a measure of whether lymph nodes have been affected
  • Metastasis – The degree to which the cancer has spread to other organs of the body

The TNM information, along with other tests, helps determine the stage of your bowel cancer using the guidelines below:

Stage O

The cancer is in its earliest stage and has not spread beyond the inner layer (mucosa) of the colon and rectum.

Stage I

The cancer has been found in the mucosa, and has spread beyond the inner layer of the colon or rectum to the submucosa, but not to the lymph nodes.

Stage II

The cancer has spread beyond the layer of muscle surrounding the bowel and reached the outermost layers of the colon or rectum and surrounding areas, but has not spread to the lymph nodes.

Stage III

The cancer has spread to the lymph nodes, but not to distant organs.

Stage IV

The cancer has spread to distant organs (e.g. lung, liver, peritoneum) throughout the body.

Treatment for bowel cancer

There are many different types of treatment for bowel cancer. Your treatment will depend on you and your cancer.

Frequently asked questions about bowel cancerFAQs

Is bowel cancer hereditary?

Approximately 30% of bowel cancer cases are related to genetics and family history.

There are three common inherited disorders that have been linked to bowel cancer, including:

  • MYH – Associated Polyposis (MAP) – This is caused by a genetic mutation in the gene MYH gene which results numerous (10-100) polyps (abnormal tissue growth) which can become cancerous
  • Hereditary Non-Polyposis Colorectal Cancer (HNPCC) (known as Lynch Syndrome) This results in mutations to the genes that protect cells from growing abnormally and turning into cancerous cells
  • Familial adenomatous polyposis (FAP) – This is characterised by significant numbers (100 – 1000) of adenomatous polyps (gland-like tissue growths) in the lining of the large intestine
What causes bowel cancer?

The cause of bowel cancer is not fully known, however there are some factors which contribute to the risk of bowel cancer developing, including: 

  • Age – The risk for bowel cancer increases for people over 50 years
  • Certain life-style related factors – Such as being overweight, drinking alcohol, a diet high in processed and red meat, and smoking
  • Family history – Including bowel cancer and bowel diseases like Crohn’s disease or ulcerative colitis
How common is bowel cancer?

Bowel cancer is very common, affecting 1 in 13 Australians. This is one of the highest rates of bowel cancer in the world. It affects both men and women, young and old, with the disease being more common in people older than 50. 

What can I do to decrease my risk of bowel cancer?

There are a number of lifestyle-related factors you can consider to reduce your risk of developing bowel cancer, like:

  • Get regular exercise – Cancer Australia recommends at least 30 minutes of moderate-intensity exercise each day
  • Reduce your alcohol intake – If you choose to drink, try to limit your alcohol intake to no more than two standard drinks a day
  • Eat a healthy, balanced diet – Eat a fibre-rich diet from grain and legume sources, as well as enjoy a variety of fruit (2 serves) and vegetables (5 serves) per day, limit your intake of salt, saturated fats, and avoid all processed meat
  • Regular screening for bowel cancer – The Cancer Council Australia recommends regular (2 yearly) screening for over 50’s using a faecal occult blood test (FOBT), which tests for the presence blood in your bowel motion. This test can be done in the privacy of your own home
How do you know if it’s bowel cancer or haemorrhoids (piles)?

Haemorrhoids, or piles, are soft lumps of enlarged blood vessels around and inside the anus. They usually result from a sudden increase in pressure – such as during pregnancy, constipation, or heavy weightlifting. Symptoms of haemorrhoids can include: 

  • Painful bowel motions
  • Bright red blood on toilet tissue, or in the stool
  • Extreme itching around the anal area
  • A lump or swelling around the anus

Because the symptoms of haemorrhoids and bowel cancer can be similar, it is extremely important to see your GP or healthcare professional if you are experiencing any symptoms of haemorrhoids or bowel cancer so that a diagnosis can be made.

Where can I find out more about bowel cancer screening?

For more information on bowel cancer screening, you can have a look at Bowel Cancer Australia.

Are there clinical trials available for bowel cancer that I can participate in?

Icon delivers Australia’s largest private cancer clinical trials and research program participating in international and national trials across medical oncology, haematology and radiation oncology. If you would like more information on participating in a clinical trial, please speak with your doctor.

See current clinical trials delivered by Icon Cancer Centre.


For a full list of references, click here.
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  2. Haemorrhoids. (n.d). Healthline. Retrieved on 13th February 2019 from
  3. Bowel cancer symptoms (n.d). Bowel Cancer Australia. Retrieved 14th February 2019 from
  4. Bowel cancer staging. (n.d). Bowel Cancer Australia. Retrieved 14th February 2019 from
  5. Bowel Cancer. (n.d). Cancer Council. Retrieved on 14th February 2019 from
  6. Bowel Cancer prevention (2018). HealthDirect. Australian Government Department of Health. Retrieved on 14th February 2019 from
  7. Bowel cancer screening (2019). Cancer Council. Retrieved on 14th February 2019 from
  8. Treatment options for bowel cancer. (n.d). Bowel Cancer Australia. Retrieved on 15th February 2019 from
  9. Finding bowel cancer early.(2018). Cancer Council SA. Retrieved on 15th February 2019 from
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