Nicotine has been noted to directly cause cancer through a number of different mechanisms such as the activation of MAP Kinases. Indirectly, nicotine increases cholinergic signalling (and adrenergic signalling in the case of colon cancer), thereby impeding apoptosis (programmed cell death), promoting tumor growth, and activating growth factors and cellular mitogenic factors such as 5-LOX, and EGF.
A study, in Sweden, showed an increased incidence of birth defects in the babies/foetuses of pregnant women who use nicotine replacement therapy (such as NRT patches) during their pregnancy.
Nicotine also promotes cancer growth by stimulating angiogenesis and neovascularization. In one study, nicotine administered to mice with tumors caused increases in tumor size (twofold increase), metastasis (nine-fold increase), and tumor recurrence (threefold increase).
What smokers aren’t being told about nicotine based e-cigarettes is that when they switch from ‘smoking’ to ‘vaping’ there remains in their lungs huge amounts of tar comprising the estimated 4000 toxic chemicals that you are supposed to not get with electronic cigarettes. That tar typically takes 10-20 years to fully ‘disperse’.
The fact is that the vast majority of lung cancer cases occur not in smokers, but in ex-smokers. For example, something like 50% of diagnosed lung cancers occur in ex-smokers who last smoked 10 or more years before their diagnosis.
So when you switch from a tobacco cigarette to an electronic cigarette all you are doing is to continue to bathe the tar and toxins that remain in your lungs with nicotine, with all of its cancer/tumour promoting qualities.
So, when vaping, you might well be less smelly, your skin might not yellow, and you might 'feel' fitter without all of the carbon monoxide in your bloodstream, and you might have more money in your pocket because e-cigs are cheaper etc. etc.
BUT, the bottom line is that there is every reason to believe that the likelihood of suffering a terminal lung disease such as lung cancer, are absolutely no different to if you had continued smoking tobacco - because of the continued interaction between the inhaled tumour promoting nicotine and the 4000 toxic chemicals present in the tar that remains in an ex-smoker’s lungs.
E-Cigarette Health Warning
The Best Way to Stop Smoking