Re: Is it true those who frequently catches cold is less likely to get cancer?

     While I'm not sure the specific example you give is part of the 
current debate, many people now believe that exercising your 
immune system (especially when you are young) can prevent 
illnesses.  The idea being that the immune system is like your 
muscles.  If you don't use your muscles they will atrophy (shrink).  
And once atrophied, even when you do need to use them, they won't 
work properly.  
     The main concern, though, is over the increase in asthma and 
respiratory problems (like allergies) in developed countries.  {An 
article in Pulmonary Reviews May 2000 gives a good summary of the 
issues.  See website: 
 "http://www.pulmonaryreviews.com/may00/pr_may00_epidemic.html"} 
 Several studies have suggested that 
children who are not exposed to pathogens (viruses, bacteria, 
parasites, fungi) are more likely to develop asthma or upper 
respiratory problems.  (This is called the hygiene hypothesis.)   There 
are even studies which indicate that exposing a child in the first year 
of life to a pet (dog or cat) can also decrease the likelihood of that 
child developing allergies. While these correlations seem quite tight, 
there are other factors that may also influence the development of 
asthma and other respiratory diseases, like genetics, development 
of the fetus,and interactions with the environment during 
development.
     Now how does this relate to cancer?  It turns out that our immune 
system is responsible for fighting cancer cells in addition to fighting 
pathogens.  If the hygiene hypothesis is correct, having lots of 
infections as a young person would protect you from getting cancer 
when you are older (and your risk of cancer increases).  As I 
indicated above scientists and physicians are still in pursuit of an 
answer.  
     No one is advising people to intentionally get colds or other 
illnesses to protect against future disease.  However, we may in the 
future discover that getting colds and infections as a young person 
may not be as bad for us as we now fear.