Simplify the following text for a Grade 7 native English-speaking person.
Original: Cancer found outside of the lung may be determined to have arisen within the lung , as lung cancers that metastasize , i.e. spread , often retain a cell marker profile that allow a pathologist to say , with a good deal of certainty , that the tumor arose from the lung , i.e. is a primary lung cancer .
Simplified: However , there are certain types of lung cancers that appear in otherwise healthy patients who have never smoked . There are 2 main types of Lung cancer , small cell lung cancer and non-small cell lung cancer .