You are right: In most cases Smoking + x(genetics, influenza...??) triggers the lung cancer.
But in the majority of cases cases X alone will not be enough.
Interpreting statistical data is not an easy task (no black an white, it's more or less grey).
To expand the analogy:
- Patients with lung cancer: 85-90% smokers
- Healthy controls: 25% smokers
- You can easily find someone with lung cancer, who never smoked
- In a group of smokers, there will be (nearly) no one with lung cancer
- In a group of smokers, only a minority will die from lung cancer
- In an animal model with a normal concentration of cigarette smoke, you will get no dramatic results
- Germany's ex chancellor just celebrated his 90th anniversary, he is a heavy smoker.
At a first glance one may argue, there are many many healthy smokers and the animal model shows nothing dramatic, therefore the association between smoking an lung cancer is weak. Further investigation is not needed.
But if there were no smokers in Germany, one would have approx. 30000 new cases of lung cancer per year less (may be 10000 remaining).
Lung cancer is a fast disease (90% dead after 5 years) whereas MS is slow (nearly full live span).
May be smoking<>cardiovascular-disease is the better analogy.
Using Zivadinovs preliminary data, there is a chance, but no proof yet, for this scenario:
If a young adult shows first signs of MS and is diagnosed with ccsvi and the ccsvi can be treated, then the progression of ms is stopped or slowed down. Again no 0 or 1, may be only in 50% of cases or more or less. Same may be true for a later stage of the disease.
Another consequence is, that if a physician tells you, that these slight malformations are very common, so everything is ok, for many diseases this might be wrong. Better: These slight malformations are very common, but if you show any signs of the disease XY, then we have to address this immediately .