Some lung cancers produce abnormally high blood levels of certain hormones or substances such as calcium. If a person shows such evidence and no other cause is apparent, a doctor should consider lung cancer.
Lung cancer, which originates in the lungs, can also spread to other parts of the body, such as distant bones, the liver, adrenal glands, or the brain. It may be first discovered in a distant location, but is still called lung cancer if there is evidence it started there.