A new study out of Taiwan found that nicotine can increase breast cancer tumor growth in vitro (that is, in laboratory situations where the cells are removed from the body and subject to some very specific artificial stimulation, typically involving quantities far in excess of anything actually experienced in the body). Despite how this is being spun, this is not news: It has long been known that nicotine can promote growth of cancer cells under the right circumstances, in laboratories and in extracted cells. It is also possible that nicotine promotes actual cancer growth in people, but it is clear from decades of research on smoke-free nicotine users that if it does, it is sufficiently rare that it is impossible to detect. Indeed, the link between smoking and breast cancer is among the weakest for any cancer among older adults.
As with anything scary (especially when it involves some evil chemical), the news media is trying to spin this as a scary new discovery. What is worse, though, is that anti-public-health activists among the anti-tobacco community will inevitably start spinning it as a reason to avoid harm reduction. They know that it will be pretty easy to trick women smokers who are paranoid about breast cancer (even though they should be more worried about lung cancer) into believing that this theoretical risk that has been shown to be very small, at worst, is evidence that they might as well smoke rather than switching to a low-risk nicotine source.
So far I do not see any evidence of this being used for anti-harm-reduction propaganda, but I suspect I am only a few hours ahead of them. Interestingly, some of what has been published already refers to “the nicotine in cigarettes” as the culprit, presumably to try to avoid discouraging the use of pharmaceutical nicotine. But I have little doubt that the message will evolve into “THR is bad but nicotine from pharma is fine”.
I realize that the anti-tobacco extremists will reach thousands of times as many people with their misleading messages as the science community can ever reach, but since I have already been asked about this by the e-cigarette community, here is the bottom line:
-Yes, nicotine can promote cancer cell growth in the laboratory. That has been known for a long time.
-Nicotine products that do not involve smoke have not been definitively shown to cause actual cancer in actual people after many studies of smokeless tobacco. To the extent that there are claims about cancer risk, they are focused on one or two specific cancers (with no backing for claims about breast cancer — the only study to ever suggest that was withdrawn by the authors as fundamentally flawed). This makes clear that any cancer-promoting effect of nicotine for breast cancer or most other cancers is so small that no one has even seriously claimed to have found a hint of it, let alone shown it to be big enough to matter.
-Like caffeine, soda, eating dessert, beer, bicycling, driving to the movies, and delaying the birth of your first child (a real cause of breast cancer risk), from what we know using nicotine increases your risk of premature mortality a bit. Avoid it entirely if this matters more to you than the benefits it provides. But if you smoke, you should worry about the very clear risk of lung (and other) cancer from not switching to a smokeless product, rather than the completely speculative risk that the alternative nicotine product might create some too-small-to-measure risk of breast cancer.
Addendum: It is worth noting that the researchers who conducted and published the actual scientific study did not draw any unwarranted conclusions about the practical implications of their findings. To their great credit, they stuck to doing the science that they knew, and did not wander off into making epidemiologic and economic conclusions or political diatribe as most Western authors writing on this topic would. However, the editor of the (American) journal that published the article started trying to spin this as having implications for actual health outcomes, even though these are purely speculative. No, I am not being racist or culture-ist — I think the difference comes down to the fact that adding an anti-tobacco extremist rant to any remotely-related study report is a good way for an American or European to guarantee future support from those in power.
– Carl V. Phillips