Patients with diabetes mellitus have a higher risk of developing colon cancer, researchers from the University of California, Berkeley, reported in the American Journal of Gastroenterology. The authors stated that according to their findings, diabetes is an independent risk fact for rectal and colon cancers. A person with diabetes has a 38% higher risk of developing colon cancer compared to other people. Male diabetes patients were found to have a 20% higher risk of developing rectal cancer.
However, the researchers added that they are not sure what causes the link between diabetes and colon cancer risk, and therefore cannot determine what can be done about it. Some experts speculate that hormones might be playing a part. Diabetes patients have high insulin (a hormone) levels, as well as high levels of growth factors. These hormones help cells, including cancer cells, to grow and move on to other parts of the body.
The researchers explained that diabetes mellitus has been linked to higher colorectal cancer risk. According to 2008 ACG (American College of Gastroenterology) Guidelines for Colorectal Cancer Screening, doctors are told to be on the lookout for CDC (colorectal cancer) risk in patients who are obese and those who smoke – but it does not mention an increased risk for those with diabetes.
Hiroki Yuhara and team set out to find out whether diabetes might be linked to colon and/or rectal cancer risk. They carried out a meta-analysis (combining the results of many different studies) of case-control and cohort studies. They looked at 14 international studies. They also tried to determine whether risks varied according to sex. The authors stressed that they took into account variables which might affect the results, such as smoking, obesity and levels of physical activity.
They found that people with diabetes had an 38% greater chance of developing colon cancer, compared to those without diabetes. Increased risk of rectal cancer was only detected among males with diabetes – a 20% higher risk.
The authors stressed that the observational studies they looked at do not compellingly prove that diabetes directly contributes to colon cancer – it just revealed that there appears to be a greater risk for people with diabetes.
Researchers earlier on this year found that older female diabetes patients have more than double the risk of developing some kinds of colorectal cancer compared to women of the same age without diabetes. Colorectal cancer is the third leading cause of deaths from cancer in the USA. (Link to article)
In 2006, scientists from the Mayo Clinic Cancer Center, University of Cincinnati and the H. Lee Moffitt Cancer Center, found that diabetes patients who were also regular smokers face the highest risk of developing colon cancer. (Link to article)
Written by Christian Nordqvist