About bowel cancer

What is the bowel?

The bowel is part of our food digestive system. It is divided into the small bowel and the large bowel, and connects the stomach to the anus (bottom) where waste material (called a bowel motion, faeces or poo) is passed out of the body. The large bowel is where cancer most often develops.

Diagram showing the digestive tract, which runs from the mouth to the anus. It labels the small bowel, the colon, the rectum and the anus.

What is bowel cancer?

Bowel cancer is also called colon, rectal or colorectal cancer.

Bowel cancer occurs when normal cells lining the inside of the bowel become abnormal and grow out of control. The cells can turn into a polyp (growth) and some polyps may eventually develop into cancer over a number of years.

It can take a long time before the cancer grows and spreads to other parts of the body.

Regular bowel screening, of people who are not experiencing any symptoms, provides an opportunity to find and treat bowel cancer at an early stage.

Symptoms of bowel cancer

Common symptoms of bowel cancer may include:

  • a change to your normal pattern of going to the toilet that continues for several weeks
  • blood in your bowel motion.

Although these symptoms are usually caused by other conditions, it’s important to get them checked by your doctor.

Who is at most risk of bowel cancer

Bowel cancer is more common in those over the age of 60, and is more common in men than in women.

People who have had extensive inflammatory bowel disease, or have a family history of bowel cancer, may have a higher risk of developing bowel cancer. Go to About the test to find out if you should talk to your doctor about your risk.

What you can do to help reduce your risk

Scientists are still unsure what causes bowel cancer. It often starts as a benign (not cancerous) polyp (growth) that turns into cancer over time.

A diet relatively high in red meat and animal fats and low in fruit and vegetable fibre may contribute to the development of bowel cancer. Lack of exercise can also be a risk factor.

To help reduce your chances of developing bowel cancer:

  • eat a healthy diet high in fruit, vegetables and fibre
  • exercise regularly
  • don’t smoke.

You can find advice on the Ministry of Health website on:

Page last updated: 05 May 2017
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