A person's lung cancer diagnosis depends on the type of lung cancer present. The two main types of lung cancer are small cell lung cancer and non-small cell lung cancer. Non-small cell lung cancer is more common than small cell lung cancer. These categories refer to what the cancer cells look like under a microscope.

The extent of disease is referred to as the stage. Information about how big a cancer is or how far it has spread is often used to determine the stage. Doctors use information about stage to plan treatment and to monitor progress.