The bowel is part of our digestive system and starts at the mouth and ends at the anus. The bowel helps the body break down food and turn it into energy. It also deals with parts of the food the body does not use.
The bowel is made up of two sections - the small and the large bowel.
The small bowel is where the nutrients from the food are broken down and absorbed into our body.
The large bowel absorbs water and salts, and turns what is left over into solid waste matter (known as poo, faeces, or stools when it leaves the body). The large bowel has three parts: the caecum, colon, and rectum.
Image courtsey of Cancer Council Victoria
Bowel cancer is the growth of abnormal cells in the large bowel (the colon or rectum).
Bowel cancer usually develops from polyps - these are growths on the inner lining of the bowel. Many people have polyps, most of which do not become cancer (they are benign). However, as polyps can be an early warning sign for bowel cancer, they should be removed when possible.
If left untreated, some polyps may become larger and the cells within may change and become malignant (cancer). When this happens, the cancer often ulcerates (becomes an open sore) and bleeds, or may cause a blockage of the bowel. Over time, the cancer is likely to spread through the bowel wall to the blood vessels and lymph nodes, and even to distant organs, especially the liver.
Bowel cancer is preventable and the best way to protect yourself is to participate in the National Bowel Cancer Screening Program as this helps to find polyps and cancer early.
How common is it?
Bowel cancer is one of the top cancers affecting men and women in Western Australia.
In 2017, 1307 people were diagnosed with bowel cancer (702 men, 605 women) and 390 died from bowel cancer (224 men, 166 women).1 The chances of getting bowel cancer by the time you are aged 85 (lifetime risk) is 1 in 13.2
Learn more about bowel cancer statistics.
The exact cause of bowel cancer is not known. However, there are a number of factors that are known to increase the risk of developing bowel cancer.
There are a number of risk factors you can change. Your risk of bowel cancer is increased if you:3,4,
- use alcohol
- have a poor diet, including inadequate fibre or too much red and processed meat
- don't exercise
- are above a healthy weight
Other risk facts that you can not control but that increase your risk:3
- age - most people with bowel cancer are over 50, and the risk increases with age
- having a previous history of bowel cancer or polyps
- a strong family history of bowel cancer
- chronic inflammatory bowel disease (ulcerative colitis and Crohn's disease)
- a rare inherited genetic disorder, such as Familial Adenomatous Polyposis (FAP) and Lynch syndrome (formerly known as Hereditary Non-Polyposis Colorectal Cancer (HNPCC)). Together they account for less than 5% of all bowel cancers.
Symptoms of bowel cancer may include one or more of the following:4
- Bleeding from your back passage (anus) or any sign of blood after a poo/bowel motion (this could be red to black)
- A change in bowel habit, for example, straining to go to the toilet (constipation) and/or looser bowel motions (diarrhoea)
- Abdominal pain and bloating
- Loss of weight for no obvious reason
- Loss of appetite
- Symptoms of anaemia, including unexplained tiredness, weakness or breathlessness
If any of these symptoms are unusual for you, and they persist for more than 4 weeks, it's important to see your doctor.
It is important to know these symptoms, but it is equally important to know bowel cancer often develops without symptoms. What's more, having these symptoms does not mean you have bowel cancer, as they may be caused by other conditions. For example, rectal bleeding may be the result of haemorrhoids or piles.1 However, if you do have blood in your poo just once, or any of these symptoms for more than 4 weeks, you should see your doctor as soon as possible.
Many people experiencing symptoms of bowel cancer delay seeing their doctor because they are embarrassed to discuss their symptoms. Unfortunately, this embarrassment may put your life at risk. It is important to put embarrassment aside and seek advice as soon as possible. Remember that the earlier a diagnosis is made, the better chances of successful treatment. As cancer progresses, the chances of survival decrease.
Bowel cancer is one of the most preventable cancers.
There are a number of things you can do to help reduce your chances (risk) of developing bowel cancer including:4
- Take part in the National Bowel Cancer Screening Program
- Quit smoking
- Achieve and maintain a healthy body weight
- Get at least 30 of moderate intensity physical activity on most days of the week
- Eat well - enjoy a wide variety of nutritious foods from the five main food groups every day. This includes:
- Eating foods which are high in fibre
- Avoiding processsed meats
- Limiting your intake of red meat to 3 or 4 palm sized serves (65-100g) a week
- Plenty of vegatables, including different types and colours, and legumes/beans
- Avoiding alcohol use. If you choose to drink, limit your alcohol intake
Screening for cancer means finding early cancer before symptoms develop. Screening does not diagnose cancer - it identifies people who need more tests to find out if cancer is present.2 Early detection of bowel cancer significantly improves the chances of successful treatment.
National Bowel Cancer Screening Program (NBCSP)
The National Bowel Cancer Screening Program invites eligible people starting at age 50 and continuing to age 74 (without symptoms) to screen for bowel cancer using a free, simple test at home.
Invitees' names are drawn from either the Medicare or Department of Veterans' Affairs enrolment records. If you are eligible to participate in the program, you will be contacted by mail and sent the screening kit, which includes a description of how to complete the test. If you need help, you can use the Invitation Pack - Home Test Instructions found here.
If you participate in the program, your results will be sent to you and your nominated doctor in the mail. Most people that are tested are likely to have a negative result (93%).5
The small number of people who have a positive test will be sent for more tests, which may include referral to undergo a colonoscopy. Only a small number of people (3%) who have this follow-up colonoscopy will have bowel cancer but many will have a pre-cancerous growth called an adenoma. These can be removed during the colonscopy.4, 5
What to do if you are ineligible for the National Bowel Cancer Screening Program
Some GPs are able to provide patients with a screening test or refer patients to a pathology laboratory to complete a test (this usually involves providing a bowel motion sample in a specimen collection jar for the pathology laboratory to test).
If you have any signs or symptoms of bowel cancer or have had a positive test, you need to visit your doctor without delay and you may be referred for further tests such as a colonoscopy. Having signs and symptoms or a positive test does not mean you have bowel cancer, but it means that something needs checking.
This can be a worrying time, especially if you need to have several tests. If the tests show you have or may have cancer, your doctor will refer you to a specialist, who will talk to you about treatment options.
What is a colonoscopy?
A colonoscopy allows the doctor to look at the inside of your bowel using a colonoscope. A colonoscope is a long, thin, flexible tube with a built-in light and camera that is connected to a video monitor.4 The colonoscope is passed into the large bowel through the anus, and the entire length of the bowel is inspected.
Any polyps or tumours (bowel cancer) that are found can be removed during the colonoscopy procedure, provided they are not too large.4
A colonoscopy is usually done under sedation.
Before undergoing a colonoscopy, you will be required to prepare your bowel. To do this, you will need to drink a large amount of bowel preparation liquid - this causes diarrhoea, which cleans and empties the bowel.
You will be given special instructions by your doctor that may include following a certain diet and fasting. It is important to follow these instructions carefully so that your bowel will be clean enough for the doctor to see everything clearly.
In some cases, you may be given an enema. This is when fluid is put into your rectum. This will give you watery diarrhoea that will empty your bowel.
What to ask your doctor or specialist?
A cancer diagnosis can be a very confusing time. There are many different cancers so it is important to find out information that is relevant to you.
There are several things you can do to help prepare for your appointment and to improve your understanding.
- It can be helpful to write a list of questions to ask your doctor or specialist. You may need to ask for a longer appointment
- Take some paper and a pen so that you can write down notes and instructions
- Take a relative or friend with you for support - it can be helpful to have an extra person to hear what is being said and write down any notes
- It may be helpful to record your visit - make sure you ask your doctor if it's okay. Remember, many smart phones and mp3 players can make audio recordings
If you have been diagnosed with bowel cancer, you should expect to be cared for by a multidisciplinary team (MDT). This is a group of doctors and other health professionals who are experts in a specific cancer who work together to plan the best treatment for you. Everyone's treatment is different and depends on the type of cancer and how far the cancer has spread.
Stages of cancer
Staging is used to determine if and how much a cancer has spread and is used to determine treatment options and survival outcomes (prognosis) for cancer patients post diagnosis.
In Australia, one of the most common staging systems for bowel cancer is Australian Clinico-Pathological Staging. It describes bowel cancer stages as:
- Stage 1: The cancer is confined within the bowel wall
- Stage 2: The cancer has spread to the outer surface of the bowel wall and not beyond
- Stage 3: The cancer has spread to lymph nodes outside the bowel wall and not beyond
- Stage 4: The cancer has spread to other parts of the body
Prognosis means the expected outcome of a disease. In most cases, the earlier bowel cancer is diagnosed and treated, the better the outcome.2
You may wish to discuss your prognosis and treatment options with your doctor, but it's not possible for any doctor to predict the exact course of your cancer. Test results, the type of cancer you have, the rate and depth of tumour growth, how well you respond to treatment, and other factors such as age, fitness, and medical history are all important in assessing your prognosis.
Types of treatment
The type of treatment for bowel cancer depends on the stage at diagnosis and can be different for everyone. If you or someone you know has been diagnosed with cancer, you may have many questions and concerns and need more information to help you make decisions about your treatment.
Although nearly all treatments have side effects, most can be effectively managed. Ask your doctor to explain what side effects to expect and how best to manage these.
Treatment for bowel cancer may be one, or a combination of the following:
Surgery is the usual treatment for bowel cancer. It involves removing the cancer as well as surrounding tissue to make sure no part of the cancer is left behind.4 Usually the bowel can be joined together again to restore normal function. If for some reason it cannot be re-joined, an artificial opening (colostomy) for faecal waste is made in the wall of the abdomen. In many cases, a colostomy is short term to allow for healing and once the bowel is healed the colostomy is removed and the bowel joined back together.
Bowel surgery is a major operation with an average hospital stay of five to 10 days followed by four to six weeks of recovery.
For those with larger tumours or whose cancer has spread to the lymph nodes, the best results are often achieved by combining surgery with radiation therapy and chemotherapy.
Chemotherapy uses anti-cancer drugs to help destroy cancer cells that may have spread to other areas of your body but cannot be detected. Chemotherapy after surgery can reduce the chance of the cancer coming back.
Radiation therapy uses x-rays to destroy cancer cells. It can be used before or after surgery for cancer to reduce the tumour size and make surgery easier. It is also used to decrease the chance of cancer coming back.
Complementary therapies can work alongside medical treatments and some have been shown to improve quality of life or reduce pain. There is no evidence that these therapies can cure or prevent cancer.
It is important to know that some complementary therapies have not been tested for side effects, may work against your medical cancer treatment, and may be expensive. Let your doctor know about all complementary therapies you are thinking of using.
For more information about complementary therapies, visit Memorial Sloan-Kettering Cancer Centre's About Herbs, Botanicals and Other Products.
Visit the National Bowel Cancer Screening Program for additional videos, factsheets and pamphlets
- Department of Health. (2020). Cancer incidence, mortality and survival in Western Australia,
2017. Information and Performance Governance Directorate. Department of Health, Perth.
Statistical Series Number 112. Avaliable from: ww2.health.wa.gov.au/Articles/U_Z/Western-Australian-Cancer-Registry-Statistics
- Australian Institute of Health and Welfare, Department of Health and Ageing. Cancer in Australia 2019. Canberra: Australian Institute of Health and Welfare, Department of Health and Ageing, 2019. Avaliable from: https://www.aihw.gov.au/reports/cancer/cancer-in-australia-2019/contents/summary#:~:text=In%202019%2C%20it%20is%20estimated%20that%20almost%20145%2C000,to%205%25%20less%20than%20the%20rate%20in%202008.
- World Cancer Research Fund/American Institute for Cancer Research. Diet, Nutrition, Physical Activity and Cancer: a Global Perspective [Internet]. ; 2017 [cited 2018 September 12]. Available from: https://www.wcrf.org/dietandcancer/recommendations-about#download_block.
Cancer Council Australia Surveillance Colonoscopy Guidelines Working Party. Clinical practice guidelines for surveillance colonoscopy. Sydney: Cancer Council Australia., cited 2020 Sep 11]. Available from: https://wiki.cancer.org.au/australia/Guidelines:Colorectal_cancer/Colonoscopy_surveillance.
- Australian Institute of Health and Welfare, Department of Health and Ageing. National Bowel Cancer Screening Program: Monitoring Report 2020. Canberra: Australian Institute of Health and Welfare, Department of Health and Ageing, 2020. Avaliable at: https://www.aihw.gov.au/reports/cancer-screening/national-bowel-cancer-screening-monitoring-2020/contents/summary