Diabetes Increases Colorectal Cancer Risk for Women

Dec. 7, 2007 — -- Women with diabetes already have to manage a complex diagnosis and treatment protocol. Now they may have another disconcerting diagnosis: colorectal cancer.

According to a study released Friday, women with diabetes are 1.5 times more likely to develop colorectal cancer -- in which cancerous tumors develop in the tissues of the colon or rectum -- than women who don't have the metabolic disorder.

The research was announced Friday at the American Association for Cancer Research's Sixth Annual International Conference on Frontiers in Cancer Prevention Research.

"We are just beginning to understand the role of insulin in the increased risk of many cancers," said Dr. Andrew Flood, the study's lead author and assistant professor of epidemiology and community health at the University of Minnesota School of Public Health.

"Our primary finding in this study was that a diagnosis of diabetes meant a 50 percent stronger chance of developing colorectal cancer."

Flood and his colleagues examined data from a large-scale cancer screening study known as the Breast Cancer Demonstration Project, which took place during the 1970s at 29 different medical facilities. They tracked the records of more than 45,000 female participants to identify how many women later developed colorectal cancer.

After adjusting for a number of variables, Flood said the results remained statistically significant, and he believes insulin has something to do with it.

"Elevated rates of insulin itself may promote the risk," he said.

Dr. David Beck, chairman of the department of colon and rectal surgery at the Ochsner Clinic Foundation in New Orleans, agrees that insulin may play a role in cancer development.

"Insulin is important in cells' ability to use glucose, one of the cells' major energy source," he said. "Elevated glucose levels might support cell growth initially or may contribute to new blood vessel growth, which would allow cells to grow faster. This might be a factor in other cancer development."