NEW YORK (Reuters Health) – Use of metformin is associated with a decreased risk of pancreatic cancer in patients with diabetes, new research shows. By contrast, treatment with insulin or an insulin secretagogue may increase the risk.

“The current study demonstrated a robust protective effect of metformin against pancreatic cancer in diabetes. Our major observations were that diabetics who ever used metformin, especially those with greater than five years of use, had a reduced risk of pancreatic cancer compared to diabetics who had not taken these drugs,” lead author Dr. Donghui Li said in a statement.

“This adds evidence to previous study findings indicating that antidiabetic therapy can affect the development of cancer,” Dr. Li, from the M.D. Anderson Cancer Center in Houston, added.

The findings stem from a case-control study of 973 patients with pancreatic adenocarcinoma and 863 controls. There were 259 diabetics in the cancer group and 109 in the control group. All but two of the diabetics had been diagnosed after the age of 18.

As reported in the August issue of Gastroenterology, metformin use by diabetics was associated with a 62% reduced risk of pancreatic cancer (p = 0.001) after accounting for potential confounding factors. Moreover, the association remained statistically significant after limiting the analysis to subjects with diabetes for longer than 2 years and to insulin never-users.

Treatment with insulin or an insulin secretagogue, however, had just the opposite effect, increasing the odds of pancreatic cancer by 4.99- and 2.52-fold, respectively.

Further research is needed to verify these findings, the authors emphasize. “If the finding that metformin is protective against pancreatic cancer is confirmed, metformin may offer a tool for the primary prevention of pancreatic cancer among people with type II diabetes,” Dr. Li added.

Reference:
Gastroenterol 2009;137:482-488.