The exact cause of bowel cancer is unknown. However, things called risk factors can increase the chance of a person developing it. Having one or more risk factors does not mean you will definitely develop bowel cancer. Equally, if you do not have any risk factors, it doesn’t mean you won’t get bowel cancer.
Bowel cancer is not infectious. You cannot pass it on to other people.
Eating a lot of red and processed meat increases the risk of bowel cancer. Red meat includes beef, lamb and pork. Processed meat includes smoked meat, ham, bacon, sausages, pâté and tinned meat. Eating fried or grilled meat may also increase the risk.
Eating two or more portions of red or processed meat a day seems to increase the risk the most. People who eat less than two portions a week have the lowest risk. No link has been found between bowel cancer and eating poultry, such as chicken and turkey.
Not eating enough fruit and fresh vegetables may also increase the risk.
Having an inflammatory bowel condition, such as ulcerative colitis or Crohn’s disease, can increase the risk of bowel cancer. People with these conditions may be offered regular bowel screening with a test called a colonoscopy.
Irritable bowel syndrome is not an inflammatory bowel condition. It does not increase the risk of developing bowel cancer.
Most people who get bowel cancer do not have a family history of it. Having one relative who developed bowel cancer at an older age does not significantly affect your risk.
If several close family members on the same side of your family have had bowel cancer, this may increase your risk. You may also have a higher risk if a close family member developed bowel cancer before the age of 50. Close family members are parents, brothers and sisters.
People who have a history of bowel cancer in their family can be referred to a specialist clinic to have their risk assessed. People at high risk of bowel cancer are offered bowel screening. This involves regular tests to look at the inside of the large bowel (colonoscopy). For more information, contact your GP or call our cancer support specialists on 0808 808 00 00.
Inherited (familial) conditions
About 5 in every 100 bowel cancers (5%) are caused by an inherited faulty gene.
There are two rare conditions that can run in families:
- familial adenomatous polyposis (FAP)
- Lynch syndrome (also called hereditary non-polyposis colorectal cancer or HNPCC).
People with either condition have a very high risk of developing bowel cancer.