Re: After smoking for 25 years, can quitting have negative effects?

Hi Jay
note that the incidence of cancer/ cardiovascular disease increases as a 
power of age; so the older you get, the incidence of cancer/ cv disease 
increases exponentially under any circumstances.

I understand that quitting smoking has no positive or negative effect on 
your chances of lung cancer; your chances of getting lung cancer just 
cease to get worse (as they would if you continued to smoke). But this 
last effect is very clear; the more you smoke, the better your chances of 
getting cancer. So giving up smoking has clear and tangible benefits.

There is obviously some physiological dependence on tobacco- e.g. the 
withdrawal symptoms of smokers giving up. Nicotine has an effect on 
cholinergic nerve transmission, and it is a very widespread nerve 
chemical which the body uses all the time; hence the short-term 
withdrawal symptoms. However, I am unaware of any other "need" for 
tobacco smoke chemicals, and I can't imagine why the immune system would 
be unable to cope. If you consider that smoking is really a chemical 
assault with nasty chemicals, you are simply removing the exposure to 
nasty chemicals, and it isn't immediately obvious why that would be bad- 
quite the opposite. With the immune system, you would clear up the lungs 
and deposits of tar, with improved circulation, and so I would expect 
much better immune function in the lungs. 

If you are interested, there is actually quite a lot of published 
information on the epidemiology of human smoking, and what happens to 
cancer incidence when you give up. I am sure you could dig up a review.

cheers
david