Researchers reported that a drug used to treat seizures, migraines and mood disorders may also prevent head and neck cancer, according to NBC News. The drug, called valproic acid, is already being tested as a possible treatment for several cancers. But a new study shows that veterans who took the drug to treat headaches, seizures, and other ailments had a 34 percent lower-than-average risk of developing head and neck cancer. The effects were clearest in smokers, a finding that suggests the drug may reverse some of the damage caused by cigarette smoke. About 40,000 Americans are diagnosed with head and neck cancer each year and about 10,000 die from it.