Lung cancer is a type of cancer that starts in the lungs. It is one of the most common cancers worldwide and is often linked to smoking, although non-smokers can also develop the disease. Lung cancer can cause symptoms such as persistent cough, chest pain, shortness of breath, and coughing up blood. Early detection is crucial for effective treatment, but lung cancer is often diagnosed at an advanced stage when it's harder to treat. Treatment options include surgery, chemotherapy, radiation therapy, targeted therapy, and immunotherapy. Quitting smoking and reducing exposure to other risk factors can help prevent lung cancer.