This study was small and related to a gene that there is not currently an easy or cost effective to isolate. Before I put too much weight on this nicotine deal, I would want to see a larger study done. Nicotine is of course not great for you, addictive and more, but no study before ever linked it to cancer, and it is not the dangerous part of tobacco products. The FDA has looked at for many different reasons extensively and not found it to be an initiator of any malignancies, hence the approval of useful nicotine replacement therapies, which while they can be addictive in their own right, have very low levels compared to cigarettes. That is one of the problems with the gum, lozenges etc. is the FDA regulates them so stringently in the US, that they actually only help 3-7% of the people that try to quit smoking using them. If only the FDA was allowed to as strictly regulate tobacco itself.