Causes of bowel cancer

A ‘risk factor’ is something that increases your chances of getting a disease. Sometimes this risk comes from something you do (for example not getting enough exercise, eating a poor diet, having a high alcohol intake, or smoking) and sometimes there is nothing you can do about the risk (for example your age or family history):

Nurses with a patientRisk Factors


Risk factors for bowel cancer that you cannot change

Below are risk factors which you cannot change. This does not, however, mean that you will get bowel cancer but that you have an increased chance of developing bowel cancer.


Bowel diseases

If you have had polyps or chronic inflammatory bowel problems (including Crohn’s disease or ulcerative colitis) you may have a higher risk of developing bowel cancer than people who do not have these conditions.


Family history and genetics

Bowel cancer can ‘run in the family’, and for around 25% of all bowel cancer cases diagnosed in the UK there is a family history.


Your ethnic background

Jews of Eastern European descent (Ashkenazi Jews) have one of the highest colorectal cancer risks of any ethnic group. Several gene mutations leading to an increased risk of colorectal cancer and other cancers have been found in this group.



Whilst bowel cancer is increasing in the younger age groups, more than 7 out of 10 people (72%) diagnosed with bowel cancer are aged 65 and over. Bowel screening is available for people aged 60 and over (50 in Scotland).


Having type 2 diabetes

People with type 2 (usually non-insulin dependent) diabetes have an increased risk of bowel cancer. Type 2 diabetes and colorectal cancer share some of the same risk factors (such as being overweight or obese). But even after taking these factors into account, people with type 2 diabetes still have an increased risk.