While I don’t know the exact answer I would expect that a significant % of lung cancer cases are attributable to smoking. There are a number of cases of people contracting lung cancer, that have no history of smoking and don’t live in a home or work around second hand smoke. Christopher Reeve’s wife (Dana Reeve)IIRC was diagnosed and died from lung cancer at an early age, and she was not a smoker.
Does anyone know the approx. % of lung cancer cases that are not attributable to smoking or second hand smoke? And if determinable, what are the leading causes of these non-smoking related lung cancers?
From this source (Link)
“The incidence of lung cancer is strongly correlated with cigarette smoking, with about 90% of lung cancers arising as a result of tobacco use”
They also discuss other causes, e.g. passive smoking, air pollution, exposure to radon and asbestos fibers and familial disposition
There was a story in the news yesterday about a new MRI technique that was revealing lung cancer much earlier than was previously possible. It cited a 15% figure for non-tobacco related lung cancer.
Yes, the figure we quote to patients is about ten percent.
Supposedly, the most common cause after smoking is due to so-called radon daughters now more often called radon progeny. Look here, too. As noted in the cites, these naturally occurring radioactive products can seep into your home from cracks in the earth.
I have heard about firemen getting lung cancer from a single exposure to toxic chemicals taken in during a fire event. Beyond radon, there must be a number of exposures people get that can cause the disease and nobody every recognizes specifically why a given individual got lung cancer without smoking. My brother smoked four packs a day from the age of 12 until he died at 80 and his lungs were clear! In the final years, they used to give him two x-Rays because they figured the first one must have been a mistake because it did not show the lungs of a smoker. Still, your chances are far better by avoiding all smoke and inhaled chemicals beyond oxygen and nitrogen.
Cite? It’d be pretty difficult to reliably attribute any form of cancer to a single exposure, save perhaps for the occasional acutely sublethal plutonium exposure events or similar.
A follow up question if I may. Is non-smoking-related lung cancer different from smoking- related lung cancer? E.g. Different mutations, more/less aggressive.
And follow up number 2. It seems that lung cancer is almost always attributable to something (smoking, chemical exposure, etc.). Why is there so much less random-generated lung cancer compare to cancers of other organs?
This is a tough question because establishing a cause of a particular case of lung cancer is difficult. There is a genetic component, making some people more susceptible, and then smoking adds to that. So someone with a family history of lung cancer, has an increased chance of lung cancer without smoking, and then increases it more by smoking. They may also develop lung cancer at an earlier age as a result of smoking, even if the genetic component is inescapable. Add in exposure to other substances, and general health considerations, and it’s difficult to define an exact percentage to attribute to smoking. In addition, those would just be percentages, and that doesn’t account well for the number of smokers who die from heart disease before they develop lung cancer.
The most conservative figure I’ve seen was that 2/3 of all lung cancer cases could be attributed to smoking (i.e. 2/3 of the people would not have lung cancer if they didn’t smoke), and in the remaining 1/3, there was still a percentage of people who would have lived longer had they not smoked. I’ve seen the 90% figure that was cited in a previous post, but I haven’t seen a percentage that high justified in terms of a 90% reduction in the number of lung cancer cases if no one ever smoked.
Even without smoking, exhaust fumes, asbestos, chemical exposure, and all the environmental causes, some people would still get lung cancer. A lot fewer people than do now, but some.
That’s a very interesting question and, indeed, there are differences. A major one is that non-smokers tend to develop the subtype of lung cancer called adenocarcinoma and rarely get so-called non-small cell carcinoma. That is pretty much the opposite of lung cancer associated with smoking. Another difference is in the response to therapy. In particular, non-smokers who get lung cancer are much more likely to respond to the class of drugs known as tyrosine kinase inhibitors. Not surprisingly, the cancers in non-smokers tend to have mutations in the tyrosine kinase receptor.
I’m not sure this is really the case except, perhaps, it may indicate that lung cancer is “less genetic” than tumours such as breast, ovary, and colon. Even more relevant is that lung cancers are very common because of smoking. In other words, if you take away the smoking-induced cases, as mentioned above, you’re left with about 10% of the total. This figure is much more in line with the rates of the other “less genetic” cancers in other organs, e.g. kidney, pancreas, bone marrow. So, maybe there’s not as much difference as there would seem to be.
Each organ has its own cancer rate, which also varies by sex and gene pools. I suppose one obvious but flippant and unhelpful answer is that every body tissue is different. I agree that without smoking, lung cancer falls quite a bit down the list (assuming the 90% number cited from smoking is correct). By “organ” prostate cancer is the big winner for frequency, especially in blacks, where it’s more than twice as common as lung cancer even when you include smoking. The lungs are surprisingly resistant and resilient organs when you consider what is thrown at them. In the case of smoking, for example, they get directly bathed in carcinogens day in and day out for decades. Yet 85% or so of smokers don’t get a clinical diagnosis of lung cancer by the time they die.
I should note that smoking increases the incidence of cancers in organs besides your lung and mouth. Those organs include the esophagus, pancreas and colorectal tract.
But that’s just for lung cancer. Overall, in round numbers, smoking will take about 10- 25 years off your stinky, dyspneic, hacking, occasionally desperate life. For everyone who smokes into a pleasant old age, there are a pack who died absolutely horrible deaths way sooner than they otherwise would have.