What is bowel cancer, and what causes it?

What is the bowel?

The bowel is part of your digestive system.

It is made up of two parts, the small and large bowel. The large bowel is made up of the colon and the rectum. The lower part of the large bowel is called the rectum. Cancer of the small bowel is very rare so the term bowel cancer nearly always means cancer of the large bowel.

Food that we eat passes from the stomach, into the small bowel and finally into the large bowel.

Nutrients are absorbed from the food and waste is held in the rectum until it is passed from the body in a bowel motion.

What causes bowel cancer?

The exact cause of bowel cancer is unknown.

It usually occurs in those over 60 years of age. However younger people may also develop bowel cancer.

Your risk of getting bowel cancer is higher if:

  • You eat a diet high in fats and low in fruit, vegetables and fibre

  • You are obese or overweight

  • You have had a previous bowel cancer

  • A member of your immediate family (mother, father, brother or sister) or relatives (aunt or uncle) has had bowel cancer

  • You or someone in your family has or had polyps. A polyp is an abnormal growth of tissue in the lining of the bowel. Polyps are usually benign (not cancer), but if left untreated, can sometimes lead to cancer

  • You or someone in your family has a bowel condition called familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC).

  • You have a history of bowel conditions like ulcerative colitis or Crohn’s disease.

Read next: Learn about the signs and symptoms of bowel cancer and check your bowel health using our online quiz.

Date Last Reviewed: 
Monday, April 3, 2017