Bowel cancer causes - 11 known risk factors
What causes bowel cancer?
Depending on where the cancer forms, bowel cancer is sometimes called colon cancer or rectal cancer.
The exact cause of bowel cancer is not known. However, there are several risk factors that increase a person's chance of developing the disease.
Over 41,000 men and women are diagnosed with bowel cancer in the UK each year. It causes almost 16,000 deaths a year, according to Cancer Research UK.
1. Obesity and being overweight
It's estimated that around 1 in 8 (13%) of bowel cancers are linked to being overweight or obese. A study showed that when compared to people with the smallest waist circumference those with the largest waist circumference had an increased risk of bowel cancer of almost 50%. Men who are obese are almost 50% more likely to develop bowel cancer than those who are a healthy weight.
2. Inactivity & lack of exercise
Not doing enough exercise increases the risk of bowel cancer. An hour of vigorous exercise or two hours of moderate exercise every day reduces the risk of developing bowel cancer by up to 24%, according to Cancer Research UK.
People whose diets are high in fruits, vegetables and fibre, and low in saturated fat seem to have a reduced bowel cancer risk. A diet high in red and processed meat is believed to increase the risk of developing bowel cancer. The Department of Health advises people to eat no more than 70g of red and processed meat a day. A diet rich in fibre and low in saturated fat may reduce the risk of bowel cancer.
Smokers are up to 21% more likely to develop bowel cancer than non-smokers.
Even small amounts of alcohol can increase a person's risk of bowel cancer. According to Cancer Research UK, for every unit of alcohol a person drinks each day, the risk of developing bowel cancer increases by 7%.
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, called 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.
7. Other digestive diseases
Bowel cancer is strongly associated with certain other diseases. Those people considered at high risk include anyone with a personal or family history of chronic inflammatory conditions of the colon such as ulcerative colitis or Crohn's disease.
8. Previous cancer or family history
A person who has already had bowel cancer may develop the disease a second time. Those who have had lymphoma, testicular, or womb cancer (endometrial cancer) are also at an increased risk. Around 20% of people with bowel cancer have a close relative who also had it.