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What is bowel cancer?

Bowel cancer, also known as colorectal cancer, develops from the inner lining of the bowel and is usually preceded by growths called polyps, which may become invasive cancer if undetected. Depending on where the cancer begins, bowel cancer may be called colon or rectal cancer. 

Bowel cancer is the third most common cancer in both men and women in Australia  and is more common in people over the age of 50.

About 90 per cent of bowel cancers are adenocarcinomas, which start in the glandular tissues lining the bowel. Other less common types of cancer can also affect the bowel, including lymphomas and neuroendocrine tumours

Cancer can also start in the small bowel but this is a rare cancer

It is estimated that 15,540 cases of bowel cancer will be diagnosed in Australia in 2021.

The chance of surviving bowel cancer for at least five years, is 70%. 

Learn more about how Cancer Council researchers are tackling bowel cancer on a national scale.



Bowel cancer symptoms

Symptoms of bowel cancer include:

  • change in bowel habit including diarrhoea, constipation or the feeling of incomplete emptying

  • a change in the appearance or consistency of bowel movements such as thin bowel stools

  • blood in the stools

  • abdominal pain, bloating or cramping

  • anal or rectal pain

  • a lump in the anus or rectum

  • weight loss

  • unexplained fatigue

  • tiredness and/or anaemia (pale complexion, weakness and breathlessness) 

  • blood in the urine or passing urine frequently or during the nightchange in urine colour – dark, rusty or brown.



Causes of bowel cancer

Some factors that increase your risk of bowel cancer include:

  • inherited genetic risk and family history

  • inflammatory bowel disease such as Crohn’s disease

  • high red meat consumption, especially processed meats

  • polyps

  • being overweight or obese

  • high alcohol consumption

  • smoking tobacco

  • having a previous diagnosis of bowel cancer.



Diagnosis of bowel cancer

A number of tests are used to diagnose bowel cancer. Initially your doctor will give you a physical examination to feel if you have any abdominal swelling. Your doctor will also give you a digital rectal examination to check for any lumps or swelling in the rectum or anus.

Blood tests

You may have a blood test to see if there are any signs that you are losing blood in your stools. It can also check your red blood cell count as low red blood cells are common in people with bowel cancer.

Immunochemical faecal occult blood test (iFOBT)

You may have an iFOBT depending on your symptoms. The test may be used if you have abdominal pain, changes to their bowel habits, unexplained weight loss of anaemia. It is not recommended if you are bleeding from the rectum.

With the iFOBT you will take a sample of your stools at home. The sample is examined under a microscope for traces of blood which could be a sign for polyps, cancer or other bowel condition. It does not diagnose cancer but if blood is detected, your doctor will recommend a colonoscopy no more than 30 days after getting the result.

Colonoscopy

The best test for bowel cancer is a colonoscopy, which examines the length of the large bowel. Air is pumped into the colon through a flexible tube that is inserted into the anus. A camera on the end of the tube allows your doctor to look for abnormal tissue that is removed for further examination.

Flexible sigmoidoscopy is used to examine the rectum and left side of the lower colon. Any unusual tissue can be removed for further examination.

Flexible sigmoidoscopy

Flexible sigmoidoscopy is used to examine the rectum and left side of the lower colon. Any unusual tissue can be removed for further examination.

MRI

An MRI scan produces detailed cross-sectional pictures of the body and can show the extent of any tumours.

CT scan

CT scans produce three-dimensional pictures of several organs at the same time and can be used to examine the bowel.

PET scan

In a positron emission tomography (PET) scan, a small amount of radioactive glucose is injected into the body. When scanned, cancer cells will appear brighter.

After a diagnosis of bowel cancer  

After finding out you have bowel cancer, you may feel shocked, upset, anxious or confused. These are normal responses. A diagnosis of bowel cancer affects each person differently. For most it will be a difficult time, however some people manage to continue with their normal daily activities.  

Your guide to best bowel cancer care

Your guide to best cancer care offers cancer specific guides describing the high-quality care you should expect at every stage of your treatment and beyond.



Treatment for bowel cancer

Treatment for early bowel cancer

Surgery

The main treatment for early bowel cancer is surgery. The most common surgery for cancer that begins in the colon is a colectomy. The type of colectomy performed will depend on whether all or part of the colon needs to be removed.

Radiation therapy (radiotherapy)

Radiation therapy (radiotherapy) is often used before surgery for locally advanced rectal cancer and may be used in combination with chemotherapy to reduce the number and size of cancer cells.

Adjuvant treatment

Chemotherapy may be recommended after surgery for rectal or colon cancer. This aims to reduce the risk of the cancer returning.

Palliative care

In some cases of bowel cancer, your medical team may talk to you about palliative care. Palliative care aims to improve your quality of life by alleviating symptoms of cancer, without aiming to cure it.

As well as slowing the spread of bowel cancer, palliative treatment can relieve pain and help manage other symptoms. Treatment may include radiotherapy, chemotherapy or other drug therapies.

Treatment for advanced bowel cancer

Systemic treatment

Systemic treatment for advanced bowel cancer uses drugs that move through the bloodstream to reach cancer cells throughout the body. Systemic treatment can include chemotherapy and targeted therapies.

Surgery

You may be offered surgery to remove small secondary cancers if the cancer has spread to other areas of the body.

Side effects  

Treatment for bowel cancer and even the cancer itself, can cause side effects. The types and severity of any side effects you may experience will depend on the type of treatment you have and may vary from person to person. Most side effects are temporary and can be prevented, reduced or managed.    

Some of the side effects you may experience include:   

Talk to your health care team about any changes you experience during and after treatment.  

Treatment Team

Depending on your treatment, your treatment team may consist of a number of different health professionals, such as:
  • GP (General Practitioner)- looks after your general health and works with your specialists to coordinate treatment.
  • Colorectal surgeon- diagnoses bowel cancer and performs bowel surgery.
  • Gastroenterologist- specialises in diseases of the digestive system.
  • Medical oncologist- prescribes and coordinates the course of chemotherapy.
  • Radiation oncologist- prescribes and coordinates radiation therapy treatment.
  • Cancer nurses- assist with treatment and provide information and support throughout your treatment.
  • Dietitian- recommends an eating plan to follow while you are in treatment and recovery.
  • Other allied health professionals- such as social workers, pharmacists and counsellors..


Screening for bowel cancer

Screening, using a non-invasive test for blood in the faeces that can be done at home, is recommended for all Australians aged 50 to 74. Known as the faecal occult blood test (FOBT), the test is only for low-risk people with no symptoms of bowel cancer. The FOBT is not for people with a family history of bowel cancer. In this case, you may need screening colonoscopies.

As of 2020 the National Bowel Cancer Screening Program, using FOBT, is now offered free every two years to all Australians aged 50 to 74. 

For further information call 1800 118 868 or visit cancerscreening.gov.au.



Preventing bowel cancer

The risk of bowel cancer can be reduced by not smoking, a healthy diet with plenty of fresh fruit and vegetables, limiting consumption of red meat, avoiding processed meats, and maintaining a healthy body weight.



Prognosis for bowel cancer

Prognosis refers to the expected outcome of a disease. It is not possible for any doctor to predict the exact course of the disease. An individual's prognosis depends on the type and stage of cancer, as well as their age and general health at the time of diagnosis. This information will also help your doctor to advise on the best treatment options. 

Generally, the earlier bowel cancer is diagnosed, the better the outcomes. 



Sources

  • Understanding Bowel Cancer, Cancer Council Australia © 2021. Last medical review of source booklet: January 2021. Expert 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. We also thank the health professionals, consumers and editorial teams who have worked on previous editions of this title.
  • Australian Institute of Health and Welfare. ACIM (Australian Cancer Incidence and Mortality) Books. Canberra: AIHW.