The way I understood this study by what I heard in a Dr. Sinclair interview is that the supplement enhances blood flow to the body. If you have certain cancers particularly lymphatic or related areas, or if it is of the type more likely cross the blood - brain barrier, the enhanced functioning and improved blood flow might increase the spread of cancer in the body. The supplementation is not the cause of cancer that is a derivative of B3 vitamin, and naturally occurs in our bodies. I shouldn't be afraid of enhanced performance or oxygenation of the body. This study is misleading and rubbish.