Bowel cancer, or colorectal cancer, can affect any part of the large bowel (colon) or rectum.

What is bowel cancer?
Bowel cancer, also known as colorectal cancer, can affect any part of the large bowel (colon) or rectum; it may also be referred to as colon cancer or rectal cancer, depending on where the cancer is located. 
The colon and rectum together are known as the large bowel.
The colon (the first 1.8 metres of the large bowel) mainly absorbs water and the rectum and anal canal (the last 15 centimetres of the large bowel) stores waste material (faeces) until they are passed from the body through the anus.
The anal canal ends at the anus, the opening of the large intestine to the outside of the body.
Anal cancer is different from and less common than bowel cancer. (Find out more about anal cancer here.)
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Most bowel cancers start as benign, non-threatening growths – called polyps – on the wall or lining of the bowel.  
Polyps are usually harmless; however, adenomatous polyps can become cancerous (malignant) and if left undetected, can develop into a cancerous tumour.
In advanced cases, the cancerous tumour can spread (metastasise) beyond the bowel to other organs.

Who gets bowel cancer?
Bowel cancer affects men and women, young and old.
Australia has one of the highest rates of bowel cancer in the world; 1 in 13 Australians will develop the disease in their lifetime.
Bowel cancer is Australia's second deadliest cancer.
Around 30% people who develop bowel cancer have either a hereditary contribution, family history or a combination of both. The other 70% of people have no family history of the disease and no hereditary contribution.
The risk of developing bowel cancer rises sharply and progressively from age 50, but the number of Australians under age 50 diagnosed with bowel cancer has been increasingly steadily. That’s why it’s important to know the symptoms of bowel cancer and have them investigated if they persist for more than two weeks.
98% of bowel cancer cases can be sucessfully treated when detected early.
Visit Bowel Cancer Australia's bowel cancer facts web page for further information.

What are the symptoms of bowel cancer?
During the early stages of bowel cancer, patients may have no symptoms, which is why screening is so important.
Minor changes in bowel movements, with or without rectal bleeding are also seen, but they are often ignored or attributed to haemorrhoids.
As a cancerous tumour grows, it can narrow and block the bowel.
Cancers occurring in the left side of the colon generally cause constipation alternating with diarrhoea, abdominal pain and obstructive symptoms, such as nausea and vomiting.
Right-sided colon lesions produce vague, abdominal aching, unlike the colicky pain seen with obstructive left-sided lesions.
Anaemia (low red blood cell count) resulting from chronic blood loss, weakness, weight loss and/or an abdominal mass may also occur when bowel cancer affects the right side of the colon.
Patients with cancer of the rectum may present with a change in bowel movements; rectal fullness, urgency, or bleeding; and tenesmus (cramping rectal pain).
Any of the below symptoms could be indicative of bowel or rectal cancer and should be investigated by your GP if they persist for more than two weeks.
  • Blood in the stool or rectal bleeding
  • A recent, persistent change in bowel habit, especially if severe (including diarrhoea, constipation or the feeling of incomplete emptying)
  • A change in the shape or appearance of bowel movements (e.g., more narrow than usual)
  • Abdominal pain or swelling
  • Pain or a lump in the anus or rectum
  • Unexplained anaemia
  • A feeling that the bowel has not emptied completely after a bowel movement

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What factors increase my bowel cancer risk?
There are two kinds of risk factors for bowel cancer – those that can be changed (modifiable) and those that cannot (non-modifiable).
Bowel cancer risk is increased by smoking, eating red meat (especially when charred), eating processed meats (smoked, cured, salted or preserved), drinking alcohol, and being overweight or obese.
These risks can all be addressed through diet and lifestyle changes and are referred to as modifiable.
Age, family history, hereditary conditions and personal heath history can also influence bowel cancer risk. Because they cannot be changed they are referred to as non-modifiable.
People with certain diseases and illnesses seem to be more prone to developing bowel cancer.
These include Type II diabetes, other forms of closely linked cancer such as ovarian or digestive system cancers, and inflammatory bowel diseases (IBD) including Crohn’s and ulcerative colitis.
A person’s risk category also depends on how many close relatives have bowel cancer and their age at diagnosis.
Someone with several close relatives diagnosed with bowel cancer before age 55 has a much higher risk than someone with no close relatives with bowel cancer.
In some family members, bowel cancer develops due to an inherited gene mutation. Some of these cause specific conditions, such as Lynch syndrome, familial adenomatous polyposis (FAP), or attenuated familial adenomatous polyposis.
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How can I reduce my bowel cancer risk?
Diet & lifestyle
Healthy diet and lifestyle choices, as well as screening and surveillance, can help to reduce your bowel cancer risk.
Evidence reveals quitting smoking, abstaining from or limiting alcohol consumption, and eating foods containing dietary fibre are all beneficial.
Maintaining a healthy weight and engaging in regular physical activity have also been shown to reduce the risk of colon cancer, but not rectal cancer.
Additionally, people who are more physically active before a bowel cancer diagnosis are less likely to die from the disease than those who are less active.
For people aged 50–70 years without symptoms or a family history of bowel cancer, a GP may also recommend taking a low dose of aspirin for at least 2.5 years.
Whether or not a person should take aspirin depends on their general health, and whether they have another condition that could be made worse by aspirin (e.g. allergy to aspirin, stomach ulcers, bleeding problems or kidney problems).
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Bowel cancer screening
Bowel cancer screening is safe and easy and can be done at home.
It is medically recommended that people aged 50 and over who do not have a family or personal history of bowel cancer, or an inherited gene mutation, should screen using a Faecal Immunochemical Test (FIT) every 1 to 2 years.
Screening involves placing small samples of toilet water or stool on a special card provided as part of a faecal immunochemical test (FIT).
The kit includes a postage paid envelope, in which the samples are mailed to a pathology laboratory.
Following analysis, the results are sent to the individual and their GP.
By 2020, Australia will have a tax-payer funded National Bowel Cancer Screening Program (NBCSP), whereby people aged 50-74 will receive a tax-payer funded screening test in the mail every 2 years.
A positive result means blood has been detected in the samples. It does not necessarily mean bowel cancer is present but does require further investigation by a GP and a referral for colonoscopy within 30 days.
A negative result means blood has not been detected in the samples; however, it does not guarantee no cancer is present or that the person will never develop bowel cancer.
The at-home test is able to detect blood, otherwise invisible to the naked eye. Blood in the stool is one possible symptom of bowel cancer. If the result of the test is positive, the person is contacted to arrange a colonoscopy.
For people ineligible to participate in the government program, a BowelScreen Australia screening test can be purchased from participating pharmacies or through Bowel Cancer Australia by calling our Helpline on 1800 555 494.
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Bowel cancer surveillance
People from families with bowel cancer need extra testing to find bowel cancer early.
This includes having a colonoscopy every five years.
The age at which a person should start regular bowel check-ups depends on their risk category.
They may also be advised to start taking low-dose aspirin regularly from age 25.
If you think you have a family history of bowel cancer or an inherited gene mutation, you should make an appointment with your GP to talk about your own risk.

How is bowel cancer diagnosed?
If a person experiences symptoms suggestive of bowel cancer for two weeks or longer, they should be referred by their GP to a specialist for colonoscopy within 30 days in order to investigate the cause.
Even if the person is not experiencing any symptoms suggestive of bowel cancer, if they receive a positive screen from an at-home bowel cancer screening test, known as a Faecal Immunochemical Test (FIT), they should be referred by their GP to a specialist for colonoscopy within 30 days for further investigation.
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What is a colonoscopy?
A colonoscopy is a detailed examination which looks at the lining of the entire large bowel.
During the procedure, if the specialist sees anything that needs further investigation, photographs and samples (biopsies) can be taken and simple polyps can be removed.

What is a CT scan?
Sometimes the first sign of bowel cancer is sudden blockage of the bowel.
When this happens, bowel cancer is diagnosed by computed tomography (CT scan) and an emergency operation.

What is staging?
Following a bowel cancer diagnosis, specialists determine how far cancer has spread.
This process is called cancer staging.
There are several different systems for recording cancer stage.
All these systems use codes based on letters and numbers, to indicate the extent of cancer spread and how much cancer is still in the body after surgery.
Australian specialists use a combination of these systems.
Staging is done by a combination of colonoscopy and scans, such as CT, positron emission tomography (PET scan), and magnetic resonance imaging (MRI).
Pathology testing of the cancer sample is also conducted and involves looking at cancer under a microscope and testing for genetic changes in the cancer cells.
The pathologist works closely with the surgeon to get an accurate understanding of the individual’s cancer.
This testing can help identify the best treatment for the person.
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How is bowel cancer treated?
Just as everyone is different, so is their bowel cancer treatment plan, which will be tailored to the patient’s individual circumstances.
Treatments can include surgery, chemotherapy, radiation or a combination of these.
Screening for loss of expression of mismatch repair protein (MMR) is recommended following surgery if you are under age 50.
Everyone diagnosed with bowel cancer age 70 or younger should have their tumour screened for Lynch syndrome to determine if they carry the genetic mutation.
If they do, they and their family members should receive a referral to a Specialist and a Family Cancer Clinic to discuss screening and surveillance.

Follow-up after surgery
As surgery techniques improve, recurrence rates are decreasing; however, there is a chance that the cancer can return.
Risk for recurrence of bowel cancer is highest within the first five years after diagnosis. For those who have had bowel cancer previously no matter how long ago, there is a greater chance of developing new bowel cancers than for those without a history of the disease.
Following initial treatment, 30-50% of bowel cancer patients in remission develop recurrence, typically within the first 2 - 3 years. If it does, it may or may not cause symptoms.
Regular check-ups should occur every 3-6 months for the first year, every 6 months for the next 2 years, then once yearly for the following 5 years. Follow-up colonoscopy should occur 6 months after surgery. Additionally, a patient should receive blood tests to measure levels of carcinoembryonic antigen (CEA) (e.g. at each visit), a CT scan (e.g. every year), and PET scans if CEA levels start to rise.
Follow-up colonoscopy should occur 6 months after surgery. Additionally, a patient should receive blood tests to measure levels of carcinoembryonic antigen (CEA) (e.g. at each visit), a CT scan (e.g. every year), and PET scans if CEA levels start to rise.
Additionally, a patient should receive blood tests to measure levels of carcinoembryonic antigen (CEA) (e.g. at each visit), a CT scan (e.g. every year), and PET scans if CEA levels start to rise.
A novel blood test to detect bowel cancer recurrence has been developed by Australian scientists from CSIRO, Flinders University and Clinical Genomics (manufacturer and pathology service provider for the BowelScreen Australia® program).
The 2-gene (BCAT1 and IKZF1) liquid biopsy targeting tumour DNA has been launched in the US and is due for release in Australia in 2017. If successful, the test could replace the CEA monitoring regime currently being used.

What if the cancer returns or spreads?
If specialists suspect that bowel cancer has returned, they will arrange a CEA test, CT scan of the chest, abdomen and pelvis and PET-CT of the colon. Other tests, such as MRI, may also be needed.
If the bowel cancer has spread (metastasised) throughout the body through the blood or lymph nodes, it will most likely affect the liver and lungs.
As with the original treatment plan, the approach taken will vary depending on the individual. RAS testing is recommended as soon as you are diagnosed with advanced (metastatic) bowel cancer (mCRC).
RAS testing is important because it can give your oncologist information they need to decide if adding a targeted therapy (precision medicine) to your chemotherapy treatments may work for you.
Personalising (or tailoring) medical treatment according to your genetic make-up helps:
  • avoid potential adverse effects from ineffective treatments
  • avoid delay in seeking alternative treatments which may be effective
  • reduce the costs of ineffective treatment.

For people with bowel cancer that is not curable by surgery, treatment aims to prolong survival and improve quality of life. 

Bowel Care Support - No one should face bowel cancer alone
Bowel Cancer Australia provides practical and emotional support for the growing number of Australians affected by the disease.
Making real change happen across the entire continuum of care, the 100% community-funded charity offers information, resources, and support to anyone with issues related to bowel cancer.
To speak with a Bowel Care Nurse please call 1800 555 494 between 10am – 4pm, Monday to Friday, or email anytime at
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