Lung cancer is the most common and deadly cancer, diagnosed in almost 220,000 people each year. It occurs due to errors in cell DNA that can be caused by smoking, radon exposure, or breathing in other chemicals daily. The main treatments are surgical removal of the tumor, chemotherapy, and radiation therapy, often used in combination. While there is no sure way to prevent lung cancer, risk can be reduced by not smoking, avoiding secondhand smoke, and eating a diet high in fruits and vegetables.