How is prostate cancer staged?

Once prostate cancer is diagnosed, the stage of cancer needs to be determined in order to decide on the most appropriate treatment plan. Staging is the process of determining if the cancer has grown within the prostate region or if it has spread to other areas of the body.

Three key factors are used to determine the cancer stage: T (the size of the tumor), N (if the lymph nodes are involved in the cancer) and M (if the cancer has metastasized, or spread, to other organs in the body).

There are two staging levels: clinical and pathologic. The clinical stage is based on information obtained before any surgery. This information is obtained from the biopsy, imaging tests and physical exams. The pathologic stage uses the same information found in the clinical stage but adds information discovered as a result of surgery.

Additional tests may be needed to help determine the clinical stage. These could include:

• Bone Scan: This is a nuclear scanning test to determine if cancer has spread to the bones. Nuclear scans use small amounts of low-energy radioactive substances to detect cancers.
• CT Scan: Dozens of low-dose x-rays are taken from various angles. A computerized tomography (CT) scan can determine the size of lymph nodes; enlarged nodes raise the suspicion of cancer within the node. A CT scan can also help see if the cancer has spread to other parts of the body.
• MRI: Magnetic resonance imaging (MRI) uses magnetic waves to produce detailed images of organs and soft tissues. MRI is useful in determining the extent of disease within the prostate gland, cancer surrounding the gland and any distant spread to other areas of the body.
• PET/CT Scanner: Radiation oncologists at Swedish were among the first in the Northwest to use a 16-slice PET/CT scanner for radiation-treatment planning. The scanner combines CT and positive emission tomography (PET), two standard medical imaging tools. The PET/CT scanner allows the tumor to be defined more precisely by better identifying the junction between cancer and inflamed normal tissue. This, in turn, allows the radiation oncologist to more effectively plan the dose of radiation to the cancer while sparing more of the healthy tissue.