COX 2 inhibitors are a type of non steroidal anti inflammatory drug (NSAIDs). These drugs block an enzyme (cyclo-oxygenase) that helps cancer cells develop. So these drugs may help lower the risk of some cancers occurring and may help to prevent cancers coming back. This is being investigated currently in clinical trials. An example of a COX-2 inhibitor is celecoxib, a drug used for arthritis pain. These drugs may increase the risk of heart attacks or strokes.