Diabetic Drugs May Slow the Spread of Lung Cancer in Diabetics, May Suppress Mesothelioma Growth as Well
Researchers at the Respiratory Institute at the Cleveland Clinic in Ohio reported that diabetic patients taking certain diabetic medications were less likely to get lung cancer than those not taking the medication. In addition, the researchers found that diabetics on the drugs prior to the diagnosis of lung cancer were less likely to have the cancer metastasize, and had a longer survival. This finding is significant for patients with pleural mesothelioma, a form of lung cancer that is most commonly found in the outer lining of the lungs, as increasing survival is a primary goal when treating the incurable disease.
Mesothelioma is a rare, aggressive form of cancer primarily caused by exposure to airborne asbestos fibers. Close to 3,000 Americans are diagnosed with the cancer yearly. Although there is no cure for mesothelioma, it can be treated with varying degrees of success through the use of surgical procedures, chemotherapy, including pemetrexed, and radiation.
The diabetic medication metformin and the class of drugs known as thiazolidedione (TZDs) work through pathways in the body that are “known to slow the growth of cancer cells, and to affect the pathways known to lead to cancer growth,” says Peter J. Mazzone, MD, MPH, lung cancer program director of the Respiratory Institute at the Cleveland Clinic.
Metformin is known to promote growth of AMP-activated protein kinase and subsequently inhibit the mammalian target of rapamycin (mTOR) that regulates cell growth in tumors, thus promoting aptopsis or death of the cancerous cells. This works in much the same way as chemotherapy.
In the report “Antifolate Modulators of Amp-Activated Protein Kinase Signaling as Cancer Therapeutics,” from the Departments of Pharmacology and Toxicology and the Massey Cancer Center, Virginia Commonwealth University, the authors concluded “pemetrexed causes a mechanistically important but indirect effect on the AMP-dependent kinase-mTOR pathway.” Pemetrexed is the chemotherapy agent often used for first line therapy of mesothelioma and non-small cell lung cancer.
Mazzone said that it is premature for diabetics to ask doctors to put them on metformin for lung cancer risk reduction. The researchers at the Cleveland Clinic concluded that “the chemopreventive and treatment effects of these [diabetic] medications warrant additional study.”
Mazzone presented his findings on November 3, 2010, at CHEST 2010, the annual meeting of the American College of Chest Physicians.
