Bowel cancer is cancer in any part of the large bowel (colon or rectum). It is sometimes also known as colon cancer or rectal cancer, depending on where it starts. Bowel cancer grows from the inner lining of the bowel (mucosa). It usually develops from small growths on the bowel wall called polyps.
On this page you will find information on:
- How common is bowel cancer?
- What are the risk factors?
- What are the symptoms of bowel cancer?
- How is bowel cancer diagnosed?
- What is the treatment for bowel cancer?
- What is the prognosis?
- What support is available?
How common is bowel cancer?
Bowel cancer is the second most common cancer affecting Australians. About 3,000 people in Queensland are diagnosed with bowel cancer every year. About one in 10 men and one in 14 women will develop bowel cancer before the age of 85. Bowel cancer is most common in people over 50, but it can occur at any age.
What are the risk factors?
While the exact cause of bowel cancer is not known, some risk factors increase the chance of developing it.
Risk factors include:
- Age – most people with bowel cancer are over the age of 50, and the risk increases with age.
- Bowel diseases – people who have an inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis, have a significantly increased risk, particularly if they have had the disease for more than 8–10 years.
- Other diseases – people who have had bowel cancer once are more likely to develop a second bowel cancer; some people who have had ovarian or endometrial cancer may have an increased risk of bowel cancer.
- Lifestyle factors – being overweight, having a diet high in red meat (particularly processed meats such as salami or ham), drinking alcohol and smoking.
- Strong family history – sometimes bowel cancer runs in families. If one or more of your close family members (such as a parent or sibling) have had bowel cancer, it may increase your risk.
- Rare genetic disorders – there are two rare genetic conditions that occur in some families. These cause a small number (5-6%) of bowel cancers. They are familial adenomatous polyposis (FAP) and Lynch syndrome.
- Polyps – having a large number of polyps in the bowel.
What are the symptoms of bowel cancer?
In its early stages, bowel cancer may have no symptoms. However, many people with bowel cancer experience symptoms. These can include:
- A change in bowel habits, such as diarrhoea, constipation, or smaller, more frequent bowel movements.
- A change in appearance or consistency of bowel movements.
- A feeling of fullness or bloating in the abdomen or a strange sensation in the rectum, often during a bowel movement.
- A feeling that the bowel hasn’t emptied completely after a bowel movement.
- Blood in the stools or on the toilet paper.
- Unexplained weight loss.
- Weakness or fatigue.
- Rectal or anal pain.
- Abdominal pain or swelling.
- Unexplained anaemia.
- A lump in the rectum or anus.
- A low red blood cell count (anaemia), which can cause tiredness and weakness.
Not everyone who has these symptoms has bowel cancer. Other conditions, such as haemorrhoids, diverticulitis (inflammation of pouches in the bowel wall) or cracks in the anal canal, can cause these changes. Changes in bowel function are common and often do not indicate a serious problem. However, any amount of bleeding is not normal and you should see your doctor for a check-up.
How is bowel cancer diagnosed?
Some people have tests for bowel cancer because they have symptoms. Others may not have any symptoms, but have a strong family history of bowel cancer or have received a positive result from a screening test.
- Physical examination – your doctor will examine your body, feeling your abdomen for any swelling.
- Blood test – to assess your general health and to look for signs that suggest you are losing blood in your stools.
- Colonoscopy – a flexible tube with a camera on the end, called an endoscope, is inserted into your anus to examine the whole length of the large bowel.
Less commonly used tests:
- Virtual colonoscopy – this uses a CT or MRI scanner to create images of the colon or rectum. It is also known as a CT colonography.
- Flexible sigmoidoscopy – blows carbon dioxide or air into the bowel to inflate it slightly and allow the doctor to see the bowel wall more clearly.
Further tests include:
- CT scan – uses x-ray beams to take pictures of the inside of your body.
- MRI scan – uses magnetism and radio waves to build up very detailed cross-section pictures of the body.
- PET Scan – injection of radioactive glucose solution to highlight abnormal tissues in the body
Some tests may be repeated during or after treatment to check how well the treatment is working. It may take up to a week to receive your test results. If you feel anxious while waiting for test results, it may help to talk to a friend or family member, a healthcare professional, or call Cancer Council 13 11 20 for support
What is the treatment for bowel cancer?
Treatment for early bowel cancer will depend on the type of bowel cancer you have. This is because colon cancer and rectal cancer are treated differently.
Your medical team will recommend a treatment based on:
- What will give you the best outcome
- Where the cancer is in the bowel
- Whether and how cancer has spread
- Your general health
- Your preference.
The most common treatment for bowel cancer is surgery. There are different types of surgery for bowel cancer. The aim of surgery for bowel cancer is to remove all of the cancer and nearby lymph nodes.
For more information on the treatment of bowel cancer please refer to the Understanding Bowel Cancer booklet.
What is the prognosis?
Prognosis means the expected outcome of a disease. You may wish to discuss your prognosis and treatment options with your doctor, but it is not possible for any doctor to predict the exact course of your disease. In most cases, the earlier bowel cancer is diagnosed and treated, the better the outcome.
To come up with a prognosis, your doctor will consider;
- Test results
- The type of cancer you have
- The rate and depth of tumour growth
- Other factors such as age, fitness and medical history.
If bowel cancer is diagnosed and treated when it is still confined to the colon and/or local lymph nodes, it is known as early bowel cancer and has a good prognosis. If the bowel cancer has spread beyond the colon and local lymph nodes, it is known as advanced bowel cancer. The cancer may respond well to treatment, but a cure is less likely.
What support is available?
Whether you have been diagnosed with bowel cancer, or have a family member or friend who is affected by cancer, there are times when you may need support. Our professional services and support programs are here to help you.
Find out more about:
- Phone support
- Email support
- Cancer counselling
- Practical and financial support
- Support groups
- Information sessions
You don’t have to face cancer alone – we’re here to help.
You can also refer to the Bowel Cancer What to Expect guide to help you make sense of what should happen, and to help you with what questions to ask your health professionals to make sure you receive the best care at every step.