Which steps are necessary to diagnose lung cancer?

Suspicion: History physical exam chest x-ray likely ct scan see a lesion, biopsy, hopefully remove!

First thing: The first step is to find a suspicious nodule or tumor in the lungs, which requires a scan (either xray or ct scan). This can be done for other reasons and find it by accident, done in screening, or done for cough or symptoms. Once a lesion is seen, it needs to be biopsied to confirm it is cancer.