Prompt Title: Causes of cancer.

The most common cause of cancer in the United States is tobacco use, specifically smoking. Smoking is the leading risk factor for lung cancer, the leading cause of cancer death in the U.S. It's responsible for approximately 80% to 90% of lung cancer cases, according to the Centers for Disease Control and Prevention (CDC). Tobacco smoke contains a deadly mix of more than 7,000 chemicals, hundreds of which are harmful, and at least 70 that are known to cause cancer.

Besides smoking, other significant risk factors contribute to the overall cancer burden, including poor nutrition, physical inactivity, obesity, heavy alcohol consumption, UV radiation exposure, and exposure to certain chemicals and pollutants. However, smoking remains the single largest preventable cause of cancer and several other diseases.