Susceptibility to lung cancer due to smoking is at least partly genetic. If you have certain variants of a specific gene (don't have time for the lit search right now), smoking won't significantly increase your chances of lung cancer.

The problem is not everyone has this gene variant, and you probably don't want to be playing Russian Roullette with your health.

OK, the gene is called CHRNA5 and it seems to be related to a nicotine receptor. Here's where I found that: http://www.nature.com/ng/journal/v40/n5/abs/ng.109.html

According to that article, the SNPs in question are rs1051730 and rs8034191. 23andme tests for both.

(My results indicate that I'm at lower risk, but I'm still not going to pick up a pack of cigarettes anytime soon :)

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.

Does this mean a person can potentially get tested for this, and find out that they have a free pass to smoke as much as they want?

That would be a very interesting scenario. few hours of testing, and we get a report like this

"Here bob, you can smoke these (a, b, c) but you can't smoke these (d,e,f). Also you can drink everything, except these (1,2,3). Now go have fun"

Smoking also causes heart disease, lung problems, etc.

Don't forget that, even if the health-care costs are zero, the financial costs of smoking are non-trivial. In addition to the costs of the cigarettes themselves, there is associated wear on one's home, car and clothes. You can also make arguments for the opportunity costs of time spent smoking, but that's harder to measure.

Don't forget that there are significant benefits to smoking as well.

Yes, even for people who it will kill. (In fact, that's probably one of the benefits for some.)

Could you expand on that? I'd be interested in hearing what the benefits are, as it doesn't seem to be something that is talked about (taboo against discussing the positive aspects of things seen as societally undesirable?).

I am a user of the e-cigarettes for these benefits he mentioned. I don't like that term, I prefer personal vaporizer, since cigarettes contain much more than just nicotine and vegetable glycol. Particularly for me, I like the increased awareness, concentration, and focus that come from the stimulant effect. When I need to do a code sprint or do a double shift, that plus coffee will keep me awake, focused, and able to work longer than I would normally have been able to. The drug is also useful for appetite suppression (similar again to coffee). Again useful for code sprints or late shifts when getting up for a snack or going for lunch would be counter-productive.

Some people claim nicotine is a relaxant in the correct dose. I have not personally experienced this, the same may not be true of the pure nicotine found in my delivery method of choice.

I won't say it's without risk. Even with e-cigs, there's not enough data to show any long term harm that they may have (although the ingredients separately and with a different vaporization method have been medically approved and are commonly found in asthma inhalers, minus the nicotine). Any stimulant use/abuse carries risks. You have to take that into account before deciding to use one, and limit yourself to using it only when you need the benefits.

Here's the Wikipedia article that explains with some sources how nicotine affects the body.

(https://en.wikipedia.org/wiki/Nicotine#Psychoactive_effects)

Ever try a nicotine patch?

I have not, no. I like the e-cig because I can carry it around in my pocket and I can use it at work only when I need the pick-me up. No worries fumbling about undoing my clothes to find a place to stick a patch. Personal vaporizers are cheaper too, and can have any flavor I like.

I smoked for a while through college and for a few years afterwards. I don't know if there are real physical benefits, but I found it relaxing. Also, going outside for a smoke break was a nice way to meet people I wouldn't talk to otherwise.

Also, it was a nice way to take a break think over what I was working on. It would also help me concentrate afterwards.

That said, now that I've quit I'll never start again...

My sister smoked in college. We're both of us somewhat anxiety-prone, and she said smoking helped her a lot around finals time, when papers were due, stuff like that.

Consider that she was addicted to nicotine, and she felt less anxious when she had nicotine. It's difficult to separate the "got what she was addicted to" from the "reduced anxiety."

She claimed that she smoked her first cigarette when she was feeling very anxious, and that it helped.

Also, she's never really been very addicted - she only smokes off and on.

No it's not difficult to separate the two. You test a bunch of people that have never smoked and see what the effects are.

I bet this has been done before.

It's difficult for someone who is self-reporting to do - if all you have is an anecdote. It's not difficult with good experimental design, which is part of my point.

I quit over two decades ago and I've not been anywhere near as lucid a thinker since. Seriously. The other night on The Doctors we saw this guest who is a doctor and never smoked in his life and nearly died from lung cancer.

edit: I'm not suggesting people should start smoking.

Smoking appears to offer some mental benefits. Some acuity-related, as described by other responders. I've also heard that smoking has mental-health benefits for some people. (We know that many folks don't respond to existing standard drugs.)

I don't actually care about what the benefits are. Instead, I think that it's important to acknowledge that they do exist.

And yes, benefits clearly do exist for some people. That's why they smoke.

There is a reduction in the incidence of Parkinson's and Alzheimer's disease in smokers.

Smoking causes cells to mutate. So no. Mutation is unpredictable and there is no "immutable" cell. Just some are more susceptible to the effects of certain common mutations than others.

Not getting cancer doesn't avoid all the other health problems. Those may not kill you but do have a significant effect on quality of life.

But sure, informed consent is a good thing.

If only it were easier to find the blog comments of the 65-year-old smokers who died of lung cancer at age 57.

A lot of the problem is that too many organisations shy away from harm reduction. They will make villains of much safer alternatives like snus or e-cigs. Many people who smoke are self-medicating. Reducing the risk to nicotine exposure from smoke exposure would go a very long way.

It depends on the person,

I got a nan, 96, walks to town 3 times a week, still rides her bike, been smoking 60 a day for 40 years, and recently cut back to 40. If i compare her to my other nan 86 frail and pretty much falling apart, now guess which one has had the better lifestyle? the second, very well off always comfortable.

At 96 i think she gets up to keep smoking, and if that keeps her alive then keep doing it.

This is like saying the dangerousness of Russian roulette "depends on the person," because you have a grandmother who's played a bunch of times and didn't die.

That's probably not correct. The grandmother playing Russian Roulette is truly the beneficiary of random chance. She's still susceptible to bullets.

The centenarian smoker likely was never susceptible to smoking-induced lung cancer in the first place.

The hammer is cocked when your embryo is conceived, and you can find out if the chamber was empty a few decades later.

Unfortunately you have to live your whole life to discover whether you're an exception or a statistic. I'll go with the statistics for my personal choices.

But most smokers will be exceptions. Most smokers will not get cancer. They get cancer significantly more often than non-smokers, but that's not scary sounding enough, I guess.

To give specific numbers, according to one study (http://www.ncbi.nlm.nih.gov/pubmed/7895211), the lifetime risk of developing lung cancer is:

   male smokers: 17%
   female smokers: 12%
   nonsmokers: 1%

Which backs up what I said. It's really unusual to see anyone talk about the actual lifetime risk. It's not as scary as saying "your chances are X times greater"... greater than what?

If those numbers are accurate, and entirely due to the effects of smoking (not just other lifestyle behaviors more common with smokers, like drinking) that's easily reason enough to quit. But even in the worst case, the fact remains, most smokers will not get cancer.

"X times greater risk" refers to the likelihood ratio over the Bayesian prior, assuming that this bit of evidence (smoking/not) is independent of other known evidence. Usually the prior is "all people" or "people of <X> ethnotype" or something like that.

You can compute the lifetime risk if you have a prior for the lifetime risk of lung cancer (1% in above example), just by multiplying.

I'm not sure where your argument leads. Are you justifying smoking as a choice, based on the numbers? Are you attempting to explain why people choose to smoke, based on the likelihood of cancer? Something else?

Regardless, smoking increases your overall risk pressure along with all of the other risky choices you can make. It's cumulative with the rest of life's choices.

What about heart disease?

Smoking causes problems other than cancer.

Yes, but I'm talking about cancer. The fact still remains that the statement "Most smokers will not get lung cancer" is a controversial statement for some reason, even though it is demonstrably true.

60 a day, at 96 years old???!! wow, that is unbelievable