Lung cancer primarily affects the lungs, which are responsible for respiration. It is predominantly caused by smoking, although non-smokers can also develop it due to exposure to secondhand smoke, radon gas, or other environmental factors. Symptoms and signs of lung cancer may include a persistent cough, hemoptysis or coughing blood, breathing problems, chest pain, and unexplained weight loss. Lung cancer is often categorized into two main types: small cell lung cancer, which is less common and usually associated with heavy smoking, and non-small cell lung cancer, which encompasses several types of lung cancers. Treatment varies and is based on the histological type and stage of cancer. It includes surgery, chemotherapy, radiation therapy, or a combination of these treatments. Early detection through screening can significantly improve prognosis.