Lung cancer is the most spreading cancer which causes most of the deaths in US. Smoking is the greatest causative of lung cancer. Chances of getting lung cancer and smoking are proportional. That means chances of getting affected increases with increase of number of cigarettes smoked. The fortunate side is that risk factors of smoking get reduced when a smoker starts quitting smoking. Within a few years, he will be completely risk free from lung cancer caused by smoking. Long term exposure to asbestos also causes lung cancer. But this chance of getting affected is exponentially higher in those who smokes and is also exposed to asbestos. It is better to have a chest X-ray to find whether you are currently affected or not. Remember, chest X-rays cannot be used to identify presence of asbestos fibres in lungs. But it will surely help in identifying lung disorders.