 Every year, 1st August is observed as World Lung Cancer Day. On this day, we need to remind ourselves of the cream fact that lung cancer is the biggest killer among all the cancers in the body. Every year, the mortality worldwide due to lung cancer is about 18 lakhs, which accounts for about 20% of all mortalities because of cancer. The most common cause of lung cancer is smoking and this smoking can be active smoking as well as passive smoking. So even if somebody in your family smokes and you do not smoke, still you are exposed to the risk of lung cancer. There are other causes of lung cancer like pollution, exposure to asbestos and the exposure to radiation.