To plan the best treatment, your doctor needs to know the type of lung cancer and the extent (stage) of the disease. Staging is a careful attempt to find out whether the cancer has spread, and if so, to what parts of the body. Lung cancer spreads most often to the lymph nodes, brain, bones, liver, and adrenal glands.

When cancer spreads from its original place to another part of the body, the new tumor has the same kind of cancer cells and the same name as the original cancer. For example, if lung cancer spreads to the liver, the cancer cells in the liver are actually lung cancer cells. The disease is metastatic lung cancer, not liver cancer. For that reason, it's treated as lung cancer, not liver cancer. Doctors call the new tumor "distant" or metastatic disease.

Staging may involve blood tests and other tests:

CT scan: CT scans may show cancer that has spread to your liver, adrenal glands, brain, or other organs. You may receive contrast material by mouth and by injection into your arm or hand. The contrast material helps these tissues show up more clearly. If a tumor shows up on the CT scan, your doctor may order a biopsy to look for lung cancer cells.

Bone scan: A bone scan may show cancer that has spread to your bones. You receive an injection of a small amount of a radioactive substance. It travels through your blood and collects in your bones. A machine called a scanner detects and measures the radiation. The scanner makes pictures of your bones on a computer screen or on film.

MRI: Your doctor may order MRI pictures of your brain, bones, or other tissues. MRI uses a powerful magnet linked to a computer. It makes detailed pictures of tissue on a computer screen or film.

PET scan: Your doctor uses a PET scan to find cancer that has spread. You receive an injection of a small amount of radioactive sugar. A machine makes computerized pictures of the sugar being used by cells in the body. Cancer cells use sugar faster than normal cells, and areas with cancer look brighter on the pictures.

Educational information provided by The National Cancer Institute (NCI) Internet site.