Diabetics may have three times the normal risk of developing colorectal cancer, researchers said Friday.
They found that a marker for raised sugar levels in blood samples could be an indicator of people more likely to develop the cancer that kills more than 490,000 people each year.
In a study of 10,000 people, those with the highest blood sugar levels, even if they were below amounts diagnosed for diabetes, were more likely six years later to have bowel cancer.
“Raised levels of blood glucose, even in the absence of diabetes, is still associated with an increased risk of colorectal cancer,” Professor Kay-Tee Khaw, of the University of Cambridge in England, said in an interview.
She and her colleagues are not suggesting that diabetes, which affects 194 million people worldwide, causes colorectal cancer but that it may be a marker for something else that increases the risk.
“We think the interpretation of this is that there are common lifestyle factors that appear to predispose to both diabetes and to colorectal cancer, such as diet or physical activity,” Khaw said.
People can have raised glucose levels without having diabetes but those with the highest levels are considered to be diabetic.
“Even levels below those (of diabetics) seem to be associated with increases in colorectal cancer,” she added.
The research, which was published in the journal Cancer Epidemiology and Biomarkers, was part of the European Prospective Investigation into Cancer study and looked into whether abnormal glucose metabolism increases the risk of bowel cancer.
Diabetes, bowel cancer share common lifestyle causes
Participants in the study filled in questionnaires about their health and lifestyle and blood samples were taken and analyzed. Six years later they were followed up and 67 had developed bowel cancer.
The people who had the most raised blood sugar levels had the highest rates of colorectal cancer -- or about three times the risk of people with the lowest blood sugar levels.
Dietary changes, losing weight and physical exercise can reduce blood glucose levels, Khaw said.
“This is giving us some clues as to what the causes of colorectal cancer might be, particularly the lifestyle factors. Diabetes and colorectal cancer may share common lifestyle causes,” she said.
“If we can identify what these factors are, then we can slow down the growth of tumors. It (the research) is providing potential in terms of identifying future treatments and potential for screening.”
But she stressed that it was a small study and that the findings must be replicated in larger research projects.