Bowel Cancer

Last reviewed: August 2026

Changes in your bowel habits can be easy to dismiss, especially when they seem minor. However, symptoms that persist or feel unusual for you should always be checked.

Complete Health Australia offers specialist investigation and care for bowel cancer. We’ll explain each step clearly, from initial testing through to treatment planning and follow-up.

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What is bowel cancer?

Bowel cancer develops when abnormal cells grow in the large bowel. It may begin in the colon, which is the main part of the large bowel, or in the rectum, the section closest to the anus. You may also hear it called colorectal cancer.

Most cases begin in the bowel lining. They often develop from polyps, which are small growths that can form inside the colon or rectum. Most polyps don’t become cancerous, but some can change slowly over several years.

Removing certain polyps can stop cancer from developing. Finding bowel cancer at an early stage can also make treatment more successful.

Bowel cancer symptoms

Bowel cancer doesn’t always cause noticeable symptoms at first. When changes do occur, they can vary depending on where the cancer is and how it affects the bowel.

Speak with your doctor if you notice:

• Blood in your bowel movements or in the toilet
• A lasting change in how often you open your bowels
• Diarrhoea or constipation that isn’t normal for you
• Abdominal pain, discomfort or bloating
• A feeling that your bowel hasn’t emptied fully
• Unexplained weight loss or reduced appetite
• Ongoing tiredness, weakness or breathlessness

Slow bleeding from the tumour can lead to iron deficiency anaemia, which may cause tiredness, weakness or breathlessness.

These symptoms can have several causes and don’t necessarily mean you have cancer. It’s still important not to delay seeking advice, particularly if they continue or worsen.

What causes bowel cancer?

It’s often not possible to identify one reason why bowel cancer develops. Changes build up within cells over time, allowing them to multiply in an uncontrolled way.

Your chance of developing the disease generally rises with age. Other factors linked with increased risk include:

• A close family history of bowel cancer
• Inherited conditions that affect the bowel
• Previous bowel polyps or bowel cancer
• Long-standing inflammatory bowel disease (IBD)
• Smoking or regularly drinking alcohol
• Eating large amounts of processed meat
• Being above a healthy weight
• Low levels of physical activity

Having one or more risk factors doesn’t mean you’ll develop bowel cancer. Some people are diagnosed without any known increased risk.

Talk with your doctor if bowel cancer runs in your family. You may need screening earlier or more often than people at average risk.

Diagnosing bowel cancer

Your doctor will ask about your symptoms, medical history and any family history of bowel cancer. Blood tests may check for anaemia, while a stool test can look for hidden traces of blood.

A colonoscopy is usually the main investigation. It allows the doctor to examine the bowel lining, remove polyps and take tissue samples if needed.

If cancer is found, scans may be used to check its size, location and if it has spread. This is called staging and helps guide treatment.

Bowel cancer screening

Screening is for people who don’t have symptoms. It uses a home test to look for tiny amounts of blood in a bowel movement.

Through Australia’s National Bowel Cancer Screening Program, eligible people aged 45 to 74 can complete a free test every two years. Those aged 50 to 74 are sent a kit automatically, while people aged 45 to 49 can request one.

A positive result doesn’t mean you have cancer, but you’ll usually need a colonoscopy. If you already have symptoms or a strong family history, speak with your doctor rather than waiting for screening.

Bowel cancer treatment

Treatment is planned around where the cancer began, its stage and your wider health. Your preferences will also form part of the conversation.

Surgery is the main treatment for many cancers that haven’t spread beyond the bowel. The surgeon removes the affected section along with nearby lymph nodes. In some cases, a temporary or permanent stoma may be needed to create a new way for waste to leave the body.

Chemotherapy may be recommended before or after surgery, or to control cancer that has spread. Radiotherapy is used more often for rectal cancer than colon cancer. Some advanced cancers may respond to targeted medicines or immunotherapy, depending on their specific features.

Your treatment is usually planned by specialists from different areas of cancer care. They’ll review the findings together and explain the approach they believe offers the most benefit.

Specialist gastroenterology support with Complete Health Australia

A possible or confirmed cancer diagnosis can leave you processing a great deal of information. Having clear guidance can make the next step feel more manageable.

At Complete Health Australia, we’ll take time to answer your questions and coordinate the investigations you need. If treatment is required, we’ll help you understand the recommendations and what to expect as your care moves forward.

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Meet our specialists

Our gastroenterology and colorectal specialists provide assessment for concerning bowel symptoms, abnormal screening results and confirmed bowel cancer.

They’ll review your medical history and test results carefully before discussing the next stage of your care. You’ll receive straightforward explanations, with the opportunity to raise concerns and involve the people close to you.

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Sources

• https://www.healthdirect.gov.au/bowel-cancer
• https://www.health.gov.au/our-work/national-bowel-cancer-screening-program
• https://www.cancer.org.au/types-of-cancer/bowel-cancer
• https://www.cancer.org.au/cancer-information/screening-tests-and-treatments/early-detection-and-screening/early-detection-of-bowel-cancer 
• https://www.cancer.org.au/cancer-information/screening-tests-and-treatments/tests-and-scans/colonoscopy