Final answer:
Lung cancer is a malignant tumor that is often caused by smoking and cannot be cured in most cases. It can be treated with surgery, chemotherapy, and radiation therapy. Smoking is the leading cause of preventable death worldwide and has harmful effects on the body.
Step-by-step explanation:
Lung cancer is a malignant tumor characterized by uncontrolled cell growth in tissues of the lung. It results from accumulated DNA damage, most often caused by tobacco smoking. Lung cancer is typically diagnosed late, so most cases cannot be cured. It may be treated with surgery, chemotherapy, and/or radiation therapy. Smoking is the single greatest cause of preventable death worldwide. It has adverse effects on just about every body system and organ. Tobacco smoke affects not only smokers but also non-smokers who are exposed to secondhand smoke. The nicotine in tobacco is highly addictive, making it very difficult to quit smoking.