Lung cancer is a type of cancer that begins in the lungs, the organs responsible for breathing. It usually starts when abnormal cells in the lung tissue grow uncontrollably, forming a tumor. The two main types of lung cancer are non-small cell lung cancer (the most common) and small cell lung cancer.

The primary cause of lung cancer is smoking, but non-smokers can also develop it. Symptoms of lung cancer may include persistent cough, chest pain, shortness of breath, coughing up blood, and unexplained weight loss. Because lung cancer can spread to other parts of the body, it's important to detect it early.

Screening programs, such as low-dose CT scans, can help detect lung cancer in people at high risk, like long-term smokers, even before symptoms appear. Early detection and treatment improve the chances of managing or curing the disease.