Stage 4:
Stage four (IV) means the lung cancer has spread to more than one area in the other lung, the fluid surrounding the lung or the heart, or distant parts of the body through the bloodstream. Once released in the blood, cancer can spread anywhere in the body, but it is more likely to spread to the brain, bones, liver, and adrenal glands. It is called stage IVA when the cancer has spread within the chest or IVB when it has spread outside of the chest.