Lung Cancer :

 Lung cancer may be a sort of cancer that begins within the lungs. Your lungs are two spongy organs in your chest that absorb oxygen once you inhale and release CO2 once you exhale.Lung cancer is that the leading explanation for cancer deaths worldwide.People who smoke have the best risk of carcinoma , though carcinoma also can occur in people that haven't smoked. the danger of carcinoma increases with the length of your time and number of cigarettes you've smoked. If you quit smoking, even after smoking for several years, you'll significantly reduce your chances of developing carcinoma .Smoking causes the bulk of lung cancers — both in smokers and in people exposed to secondhand smoke. But carcinoma also occurs in people that never smoked and in those that never had prolonged exposure to secondhand smoke. In these cases, there could also be no clear explanation for carcinoma .Doctors believe smoking causes carcinoma by damaging the cells that line the lungs. once you inhale cigarette smoke, which is filled with cancer-causing substances (carcinogens), changes within the lung tissue begin soon .At first your body could also be ready to repair this damage. But with each repeated exposure, normal cells that line your lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and eventually cancer may develop.