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Macmillan and Cancerbackup merged in 2008. Together we provide free, high quality information for people affected by cancer through our publications, website and phone service. Find out more|.
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Cancer of the large bowel (colon and rectum) is the third most common type of cancer diagnosed in the UK. Each year, approximately 23,000 people develop colon cancer and approximately 14,000 people develop rectal cancer.
Like most types of cancer, colon and rectal cancers are more common in older people – more than 80% of these cancers are diagnosed in people over 60.
In most people, the cause of colon and rectal cancer is still unknown, but research is going on to try to find the cause. We do know that some things – called risk factors – can increase our chances of developing colon or rectal cancer. These factors include eating a lot of processed meats, being overweight, getting very little exercise, and smoking.
Some people have a higher risk of developing bowel cancer as they have inherited a faulty gene.
Colon cancer and rectal cancer are not infectious and can’t be passed on to other people.
There is evidence that a diet that contains a lot of animal fat and red meat (especially processed meats such as sausages, bacon and pies) can increase the risk of developing bowel cancer.
The greatest increase in risk seems to be for people eating two or more portions of red or processed meat a day. People who eat less than two portions per week seem to have the lowest risk.
No link has been found between eating poultry such as turkey and chicken, and an increased risk of colon or rectal cancer. Eating a diet low in fruit and fresh vegetables may also increase the risk.
Cancer of the colon or rectum may be more common in people who get very little exercise and who are overweight. It’s also more common in people who have smoked cigarettes for a long time, such as 20 years or more.
People who’ve had ulcerative colitis or Crohn’s disease (diseases of the lining of the bowel) for a long time also have an increased risk of developing bowel cancer.
A person who has one or more family members with bowel cancer may have a higher risk of developing it. They are usually only at higher risk if bowel cancer has been diagnosed in a close family member (such as a parent, sister or brother) under the age of 45, or when there is colon or rectal cancer in several close members on the same side of a family.
People who are worried about bowel cancer because of their family history can be referred to specialist clinics. At the clinic their risk will be carefully assessed. Regular screening, usually with a colonoscope|, can be arranged for people who have a high risk of developing the disease.Contact your GP or our cancer support specialists for more information. You can also read our section, Are you worried about...bowel cancer?
Only about 5% (5 in every 100) of colon and rectal cancers are caused by an inherited faulty gene.
There are two very rare conditions that can run in families (familial) called familial adenomatous polyposis (FAP) and hereditary non-polyposis colon cancer (HNPCC). People with either condition have a very high risk of developing colon or rectal cancer.
People with FAP have many hundreds of thousands of benign tumours (polyps) in the lining of the colon. They will be regularly screened using colonoscopy or sigmoidoscopy to look for signs of cancer. Usually, people with FAP are recommended to have an operation to remove their colon. Unless the colon is removed, nearly everyone with FAP will develop colon cancer.
FAP causes about 1% (1 in every 100) of bowel cancers.
People with HNPCC have an increased risk of developing bowel cancers at a young age, sometimes in more than one place in the colon. Unlike FAP, people with HNPCC have very few polyps in the bowel. If you have HNPCC you are likely to be screened every couple of years using colonoscopy. Screening usually starts from the age of 25, or five years before the age at which your youngest relative developed bowel cancer.
HNPCC causes about 3% (3 in every 100) of bowel cancers.
We have further information about FAP| and HNPCC| .
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.