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Metformin May Protect Lung Cancer Patients


A drug used by millions of people who have diabetes may also help prevent progression of lung cancer. Metformin, and/or thiazolidinediones (TZDs), appears to reduce risk of advanced lung cancer and improve survival among individuals with diabetes who also have lung cancer.

Metformin may serve two important purposes in diabetes patients

Metformin (Glucophage, Fortamet), which was prescribed 41 million times in the United States in 2008, is used alone or with other medications, including insulin, to control the amount of glucose in the bloodstream of people who have type 2 diabetes. According to Peter Mazzone, MPH, MD, FCCP, of Cleveland Clinic in Ohio and the lead author of new research, “our study, as well as other research, suggests an association between metformin and/or TZDs use and the risk of developing lung cancer.”

Unlike previous studies, however, the new one, which was presented at CHEST 2010, the76th annual meeting of the American College of Chest Physicians, reported that patients with diabetes who did develop lung cancer had less advanced disease, a lesser frequency of squamous cell and small cell carcinomas, and better survival in individuals who were taking metformin and/or TZDs.

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There are two types of lung cancer: non-small-cell lung cancer (NSCLC), which makes up about 80 percent of cases; and small cell lung cancer, which accounts for the remaining 20 percent. Squamous cell carcinoma is the most common type of NSCLC. The National Cancer Institute estimates that 222,520 new cases of all types of lung cancer will be diagnosed in the United States in 2010, and that 157,300 people will die of the disease in that year.

TZDs include rosiglitazone (Avandia) and pioglitazone (Actos) (a third, troglitazone [Rezulin] was withdrawn from the market because of an increased risk of drug-induced hepatitis). Investigators in the new study reviewed data from 157 patients who had diabetes and a history of lung cancer and compared characteristics of lung cancer between those who had taken metformin and/or TZDs before their lung cancer diagnosis and those who had not taken either of the medications before their diagnosis.

The investigators discovered that compared with patients who had not taken metformin and/or TZDs before their cancer diagnosis, those who had taken any of the drugs were significantly less likely to have cancer that had spread (20% vs 42.4%) or to have small cell or squamous cell carcinoma. Patients who had taken the drugs also have a better survival rate. Both groups of patients were similar regarding age, sex, and smoking history.

For now, the researchers report that metformin appears to offer more protection against the spread and progression of lung cancer than do TZDs. However, Dr. Mazzone noted that “the findings from our completed study may lead to hemoprevention studies in at-risk groups, and, possibly, trials that add one or both of these medications to standard treatment.”

CHEST 2010 76th Annual Meeting of the American College of Chest Physicians
National Cancer Institute