Hi, there,
I'm a big believer in e-cigarettes in preference to smoking. They are the ONLY things that have kept me off cigarettes for the past year and a half (over a year before cancer diagnosis). I've told my doctors about my vaping and they list me as a "former" smoker. I'm convinced that my lung function is far better now (just had lobectomy last week) than it would have been had I not switched. Depending on where you purchase the e-liquids, the ingredients are the same (except for the nicotine) as that used in inhaler-type devices and in the "fog machines" used at concerts. I noticed a huge improvement in my breathing/lung function since switching.
That said, once I was diagnosed I researched a bit more carefully, and though there is universal agreement that nicotine isn't itself carcinogenic, there is theory/speculation that nicotine MIGHT provide a more hospitable environment for cancer cells once they have become cancer cells. IOW, it might encourage growth. Given that, I am in the process of tapering down to zero nicotine. I've gone, in the past three weeks, from 1.8 percent e-liquid (equivalent to a very light nicotine cigarette--without all the harmful products of combustion) to .6 percent. I should be down to zero in a couple more weeks.
So I would encourage your mom to discuss it with her doctor, and maybe suggest she research it for herself. If she absolutely would be smoking if e-cigarettes were not available (and let's face it, the stress of a cancer diagnosis is exactly when it's hardest to quit a deeply ingrained nervous habit), then I'm not sure it's your place to tell her doctor. Best to express your concern but keep the dialogue open.
Teri