When cancer is diagnosed, the doctor will want to learn the stage, or extent, of the disease. Staging is a careful attempt to find out whether the cancer has spread and, if so, to which parts of the body. Treatment decisions depend on the results of staging.

The doctor may order physical exams, imaging procedures, laboratory tests, pathology reports, and surgical reports to determine the stage of the cancer and if it has spread.

Some staging systems cover many types of cancer; others focus on a particular type. The common elements considered in most staging systems are:

• Location of the primary tumor
• Tumor size and number of tumors
• Lymph node involvement (spread of cancer into lymph nodes)
• Cell type and tumor grade (how closely the cancer cells resemble normal tissue)
• Presence or absence of metastasis

Most cancers can be described as Stage 0, Stage I, Stage II, Stage III or Stage IV.

Stage 0:  Early cancer that is present only in the layer of cells in which it began.

Stage I, Stage II, and Stage III:  Higher numbers indicate more extensive disease, greater tumor size, and/or spread of the cancer to nearby lymph nodes and/or organs adjacent to the primary tumor.

Stage IV:  The cancer has spread to another organ.

Cancers of the brain and spinal cord are classified according to their cell type and grade. Different staging systems are also used for many cancers of the blood or bone marrow, such as lymphoma.