New evidence that people with diabetes have a higher risk of bowel cancer comes with a surprising twist – that shared risk factors such as smoking or obesity may not be the link between the two diseases.
The review (meta-analysis) of 14 studies published in the American Journal of Gastroenterology found diabetes was associated with a higher risk of colon cancer in men and women, and a higher risk of rectal cancer in men but not women.
The big surprise was that the association between bowel cancer and diabetes remained even after known risk factors such as smoking, obesity and physical exercise were taken out of the equation.
Bowel Cancer Australia spokesman and colorectal surgeon Associate Professor Graham Newstead AM said there has been speculation that these shared risk factors were the likely reason for the association between the two diseases but this research strongly suggests otherwise.
The researchers said there were other possible mechanisms such as the high levels of insulin in diabetes affecting cells and promoting growth of tumours.
This latest research comes just weeks after the Fremantle Diabetes Study found a strong association between type 2 diabetes and bowel cancer.
“This review adds real weight to the evidence regarding the potential link between diabetes and bowel cancer. It is an area we will need to look at carefully before deciding if there needs to be specific screening recommendations for people with diabetes,” said Professor Newstead.
“At this stage, more research is needed into the relative risks of developing bowel cancer. For example, we don’t yet know whether the risk of people with diabetes developing bowel cancer is as high as the risk for people who have a first degree relative with bowel cancer,” he added.
Professor Newstead said in the interim people should remember that a bowel cancer screening test is the best way of preventing the cancer or catching it in its early stages.
“People aged 50 and over need to be screened at least every two years and if you are male with diabetes, there is now an even stronger reason for you to be taking this test,” he said.“Unfortunately our national bowel cancer screening program only offers one-off screening for people at either 50, 55 and 65 years of age, which means that many people are missing out,” he added. “BowelScreen Australia®, a home-test kit available in most pharmacies, fills that gap.”
“Everyone has a role to play in bowel cancer. People need to be aware of their individual risk factors and modify what they can. The Federal Government needs to extend their screening program so everyone aged 50 and over receives regular and appropriate screening,” said Prof Newstead.