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What is bowel cancer?

Bowel cancer is cancer in any part of the large bowel (colon or rectum). It is sometimes known as colorectal cancer and might also be called colon cancer or rectal cancer, depending on where it starts. Cancer of the small bowel is very rare – it is called small bowel cancer or small intestine cancer. For information on its treatment and management, call 13 11 20.

Bowel cancer grows from the inner lining of the bowel (mucosa). It usually develops from small growths on the bowel wall, called polyps. Most polyps are harmless (benign), but some become cancerous (malignant) over time.

If untreated, bowel cancer can grow into the deeper layers of the bowel wall. It can spread from there to the lymph nodes. If the cancer advances further, it can spread (metastasise) to other organs, such as the liver or lungs.

In most cases, the cancer is confined to the bowel for months or years before spreading. The National Bowel Cancer Screening Program aims to improve early detection.

How common is bowel cancer?

Bowel cancer is the third most common cancer affecting people in Australia. It is estimated that about 15,250 people are diagnosed with bowel cancer every year. About one in 21 men and one in 31 women will develop bowel cancer before the age of 75. It is most common in people over 50, but it can occur at any age.

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Understanding Bowel Cancer

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This information is reviewed by

This information was last reviewed January 2021 by the following expert content reviewers: A/Prof David A Clark, Colorectal Surgeon, Royal Brisbane and Women’s Hospital, and The University of Queensland, QLD, and The University of Sydney, NSW; A/Prof Siddhartha Baxi, Radiation Oncologist and Medical Director, GenesisCare Gold Coast, QLD; Dr Hooi Ee, Specialist Gastroenterologist and Head, Department of Gastroenterology, Sir Charles Gairdner Hospital, WA; Annie Harvey, Consumer; A/Prof Louise Nott, Medical Oncologist, Icon Cancer Centre, Hobart, TAS; Caley Schnaid, Accredited Practising Dietitian, GenesisCare, St Leonards and Frenchs Forest, NSW; Chris Sibthorpe, 13 11 20 Consultant, Cancer Council Queensland; Dr Alina Stoita, Gastroenterologist and Hepatologist, St Vincent’s Hospital Sydney, NSW; Catherine Trevaskis, Gastrointestinal Cancer Specialist Nurse, Canberra Hospital, ACT; Richard Vallance, Consumer.