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About bowel cancer

Bowel cancer is a malignant growth that develops inside the bowel. It is also called colon, rectal or colorectal cancer.

A malignant growth occurs when normal cells on the inside wall of the bowel become abnormal and grow out of control. The cells can turn into a polyp, which may then turn into bowel cancer over a number of years. Only about 5% of polyps develop into cancer but all but the smallest polyps should be removed to ensure they don't turn into cancer.

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

Most bowel cancers are in the large bowel, which is made up of the colon and the rectum. Occasionally the cancer is in the small bowel.

How common is bowel cancer?

New Zealand has one of the highest bowel cancer rates in the world. Bowel cancer is the second highest cause of cancer death in New Zealand. More than 2800 people are diagnosed with bowel cancer every year and more than 1200 die from the disease. By 2016 the number of new cases of bowel cancer diagnosed each year is projected to increase by 15 percent for men and 19 percent for women to 3302 (for all ages).

What are the signs and symptoms of bowel cancer?

Common signs and symptoms of bowel cancer may include:

  • a change in your normal pattern of going to the toilet that continues for several weeks (such as diarrhoea, constipation, or feeling that your bowel doesn’t empty completely
  • blood in your bowel motion

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

Who is most at risk of getting bowel cancer?

Bowel cancer is more common as you get older, particularly from the age of 50. Bowel cancer affects more men than women. A diet high relatively high in red meat and animal fats and low in fruit, vegetable fibre may contribute to the development of bowel cancer. Lack of exercise is also a risk factor for bowel cancer.

You are more at risk of developing bowel cancer if:

  • you have a history of a number of family members over two or three generations being affected with bowel cancer
  • you or a close family member have been diagnosed with bowel cancer at a young age (under 55 years)
  • there is concern that you and your family may have a genetic bowel cancer syndrome
  • there is a known genetic bowel cancer syndrome in your family
  • you have had extensive inflammatory bowel disease such as ulcerative colitis for more than 10 years.

How successfully can bowel cancer be treated?

People who are diagnosed with bowel cancer, and receive treatment when it is at an early stage, have a 90 percent chance of long term survival. If there is a delay in diagnosis and treatment, and the cancer is more advanced, it is harder to cure. Bowel screening can detect cancer early, when it can be more successfully treated.
ave the same survival rate as someone who has never had bowel cancer. If there is a delay in diagnosis and treatment, and the cancer spreads regionally, the five year survival rate drops to 70 percent, and then plummets to 10 percent where there is distant spread.

Page last updated: 19 October 2011