I find it surprising that a nicotine receptor-related gene would have anything to do with lung cancer risk, since it's supposed to be the tar in cigarette smoke

I find it surprising that a nicotine receptor-related gene would have anything to do with lung cancer risk, since it's supposed to be the tar in cigarette smoke that causes most of the carcinogenic effect, not the nicotine. I wonder if that means smokeless e-cigarettes aren't much healthier than normal cigarettes.