Tuesday, October 25, 2011

Placebo/Nocebo and the anti-smoking campaign

More people get lung cancer in spite of the fact that fewer are smoking. Today 40% more people get lung cancer than 15 years ago. The increase is biggest among women, but also among men there is an increase.  This is strange indeed, since smoking has continually gone down in the population since the seventies. A british poll show that 55 % of the male population smoked in 1970 and 22% in 2007. This trend is true for the whole western world. The strong campaigns against smoking started in the seventies and have been very successful. The risk of getting exposed to second-hand somoke has also dramatically gone down, since fewer are smoking and there is fewer public places whereyou can do it.  And still we have these facts:
 “Finding from the new American Cancer Society prospective study of 1.2 million men and women indicate that mortality risks among smokers have increased substantially for most of the eight major cancer sites causally associated with cigarette smoking. Lung cancer risk for male smokers doubled, while the risk for females increased more than fourfold.
So how can we reconcile these strange facts. We know that smoking is the major cause of lung cancer (hence the strong campaigns against it, including warning texts on tobacco products like: SMOKING KILLS!) Only 15%  of lung cancer cases occur among non-smokers and this number is stable through time. In other words, 85% of lung cancer cases still happen among smokers and 15% among non-smokers.  
Lung cancer goes up, both among smokers and nonsmokers according to statistics, habitual smoking goes down. One possible but usually completely overlooked reason for this could be that the strong campaigning against smoking in itself causes greater risk among both those who still smoke and those who fear second-hand smoke. It’s called the nocebo effect – placebos evil twin. It is the fact that fearing something or believing that something is harmful can itself harm you.
If this is true then maybe the powerful warning texts on cigarettes, as well as all the (accurate) information about the risks of smoking, could actually contribute to the problem rather than solving it.  The fact is: It has become more and more dangerous to smoke according to statistics. 
So to make my point clearer. We know that smoking is the main cause of lung cancer. Smoking has gone down since the seventies. Lung cancer has gone up. I can see three possible reasons for this strange fact. 
1. Lung cancer never was the "real" reason for lung cancer after all. But this doesn't seem right. We know (as surely we know anything) that smoking is the main cause.
2. Another unknown reason is taking the place of smoking. This also seems unreasonable to me. The other known main cause is radon, and radon in the environment has decreased since the seventies since banning asbestos.
3. Smoking has become increasingly more dangerous since the time we started to smoke less, both for smokers and those who get second-hand smoke. This I believe is the most likely reason and nocebo could conceivably play a not so small part in this. Hmm.
Very little research has been done to investigate the power of nocebo. The reason is that it would never pass an ethical committee  to suggest that people will be harmed by some inert pills, for example (and still make them take it). But what if you suggested very strongly to a whole population that something they do is extremely dangerous and harmful (SMOKING KILLS, SMOKING CAUSES LUNG CANCER) for decades? Isn't this then a huge experiment with nocebo?


  1. Actually radon is the decay product of uranium or thorium, that exist plentifully in the normal base rock. The radon gas rises up and stays in the houses that have bad ventilation of the basement. Its half-life is 3.8 days, which means that it radiates quite much..


  2. Yes, thanks for that! Unfortunately it doesn't explain the strange statistics.

  3. I think you are misreading statistics and making wrong conclusions. The articles you reference don't say what you think they say.

    In short: Mortality risk, means risk of dying from lung cancer. If you live longer and die from other causes later, mortality risk from lung cancer goes up.

    Also this: "The average age at which lung cancer is diagnosed is 71, with less than 3% of lung cancers diagnosed under the age of 45". This means that declining mortality rates from anti smoking campaigns don't affect the lung cancer rates yet.

    Lung cancer is now major smoking related cause of dead among smokers because treatments for coronary heart disease have improved. Lung cancer treatments have not improved that much.

    Summary: No more excuses and rationalizations. Quit those cigars!





  4. Anonymous:"No more excuses and rationalizations. Quit those cigars!"

    Ihave. :)

    (This argument about smoking and nocebo wasn't meant as a serious argument for anything, more a tounge-in-cheek use of statistics.)