Bowel Cancer

Written by A/Prof Viraj Kariyawasam, Gastroenterologist

1. What is Bowel Cancer?

Bowel cancer, also known as colorectal cancer, is a cancer that develops in the large bowel (colon) or rectum. It usually begins as a small growth called a polyp, which can slowly change into cancer over time.

Bowel cancer is one of the most common cancers in Australia. Importantly, when detected early, it is highly treatable and often curable.

2. Causes & Risk Factors

Most bowel cancers develop from pre-cancerous polyps over many years. The exact cause is not always known, but several factors increase risk.

Risk factors include increasing age, family history of bowel cancer or polyps, inflammatory bowel disease, a diet low in fibre and high in processed or red meat, smoking, excess alcohol intake, obesity, and physical inactivity.

3. Symptoms & How It May Present

Early bowel cancer may cause no symptoms, which is why screening is so important.

When symptoms occur, they may include blood in the stool, persistent change in bowel habits, abdominal pain, unexplained weight loss, fatigue, or iron deficiency anaemia. Symptoms can be subtle and are sometimes mistaken for less serious conditions.

4. How Is It Diagnosed?

Bowel cancer may be detected through screening tests such as the faecal occult blood test (iFOBT) or during investigation of symptoms.

Colonoscopy is the most accurate test for diagnosing bowel cancer. It allows direct visualisation of the bowel and biopsy of suspicious areas. Imaging tests such as CT scans are used to assess the extent of disease once cancer is diagnosed.

5. Treatment & Management Options

Treatment depends on the stage and location of the cancer, as well as overall health.

Early-stage bowel cancer is often treated with surgery alone. More advanced cancers may require a combination of surgery, chemotherapy, and occasionally radiotherapy. Treatment is usually delivered through a multidisciplinary cancer care team.

6. Living With / Managing Bowel Cancer

Many people treated for bowel cancer go on to live full and active lives.

Follow-up after treatment includes regular surveillance, monitoring for recurrence, and support for physical and emotional recovery. Dietary advice, exercise, and psychological support can all play an important role.

7. Prevention & Risk Reduction

Regular bowel cancer screening is the most effective way to prevent bowel cancer and reduce deaths from the disease.

Removing polyps during colonoscopy prevents cancer from developing. Maintaining a healthy lifestyle, including a fibre-rich diet, regular exercise, limiting alcohol, and avoiding smoking, further reduces risk.

8. When to Seek Medical Advice

You should seek medical advice if you have bowel symptoms such as bleeding, persistent change in bowel habits, unexplained weight loss, or iron deficiency.

Do not wait for screening if symptoms are present. Early assessment leads to better outcomes.