Risk factors for colorectal cancer

Who is at risk of colorectal cancer?

Every one of us is at risk of colorectal cancer. According to Cancer Research UK, over 38,000 people are diagnosed with cancer of the colon or rectum - sometimes also known as bowel cancer - in the UK each year. The majority of people who develop colorectal cancer have no known risk factors.

Although the exact cause of colorectal cancer is not known, there are some factors that increase a person's risk of developing the disease. These include:

Age. The risk of developing colorectal cancer increases as we age. The disease is more common in people over 50, and the chance of getting colorectal cancer increases with each decade. However, colorectal cancer has also been known to develop in younger people.
Gender. The risks overall are equal between sexes, but women have a higher risk for colon cancer, while men are more likely to develop rectal cancer.
Polyps. Polyps are non-cancerous growths on the inner wall of the colon or rectum. While they are fairly common in people over 50, one type of polyp, referred to as an adenoma, increases the risk of developing colorectal cancer. Adenomas are non-cancerous polyps that are considered precursors of, or the first step towards, colon and rectal cancer.
Personal history. A person who has already had colorectal cancer may develop the disease a second time. In addition, people with chronic inflammatory conditions of the colon, such as ulcerative colitis or Crohn's disease, are at higher risk of developing colorectal cancer.
Family history. Parents, siblings and children of someone who has had colorectal cancer are at greater risk of developing colorectal cancer themselves. If a number of family members have had colorectal cancer, the risk increases even more. A family history of familial polyposis, adenomatous polyps or hereditary polyp syndrome also increases the risk, as does a syndrome known as hereditary non-polyposis colon cancer, or HNPCC. This latter syndrome also increases the risk of other cancers.
Diet. A diet high in red and processed meat is believed to increase the risk of developing colorectal cancer. A diet rich in fibre is thought to reduce the risk of colon cancer.
Lifestyle factors. You may be at increased risk of developing colorectal cancer if you drink alcohol, smoke, don't get enough exercise and are overweight.
Diabetes. People with type 2 diabetes have a 30% increased risk of developing colon cancer.

Having one or more of these risk factors does not guarantee that you will develop colorectal cancer. However, you should talk about these risk factors with your doctor. He or she may be able to suggest ways to reduce your chances of developing colorectal cancer.