The major problem is virtually all the evidence we have is anecdotal in nature. We really do not know, physiologically, how we are successful in some instances and not successful in others. This study showed a significant increase in an immune response geared toward tumor cells. Journal of Manipulative and Physiological Therapeutics Volume 15, Number 2. Now be careful with what is being said here.
Chiropractors adjust the spine, thus affecting the nervous system.
The nervous system has been found to have certain controlling influences on the immune system. By adjusting the spine, according to these studies, certain immune functions have been raised. Quite frankly we don't know, but that is why we need more research. Instead of just dismissing it out of hand, and possibly losing a great opportunity, we must devote more time and resources to researching this.