Lung cancer is a condition in which cells divide uncontrollably in lungs. It can be caused due to long-term exposure and inhalation of toxic materials, fumes and chemicals. The signs and symptoms do not show up in the initial stages of cancer and occur only in the advanced stages. Major risk factors include smoking, exposure to second hand smoke, radon gas, asbestos, other carcinogens and family history. Lung cancer is of two types: small cell and non-small cell. Symptoms include severe cough, coughing up blood, shortness of breath, weight loss etc., Diagnosis is based on symptoms and other tests like bronchoscopy, CT scan and biopsy. The earlier it is diagnosed, the easier it can be treated with the help of medicines, chemotherapy and other options.