How Cancer Is Staged
A physician will first look at the patient's Gleason score and the results of his DRE and PSA test to determine how likely it is that the cancer has spread out of the prostate gland. If the DRE exam didn't reveal any abnormalities and the PSA level and Gleason score are low, the chances that the cancer has spread are very low. In this case, no other tests are likely to be necessary.
If it appears possible that the cancer has spread, then other tests and exams will be performed. A complete physical exam is an important part of cancer staging. The patient will be asked about symptoms, such as pain in the bones, and other parts of his body will be examined.
Imaging Tests for Cancer Staging
A number of different types of imaging tests can be used to help determine a cancer's stage.
- Radionuclide bone scan (SPECT or PET) .Prostate cancer often spreads to the bones first. In a radionuclide bone scan, the patient is injected with a tiny amount of radioactive material, called a radionuclide, that is drawn to the bones of the body. The most active cells in the bones take up more of the radionuclide than do less-active cells. Cancer cells are active and so show up as "hot spots" in the bone scan.
- Magnetic resonance imaging (MRI) . MRI scans use radio waves and strong magnets, rather than ionizing radiation. A computer translates the data into detailed images of the body's interior. An MRI can produce slices or 3-dimensional volumes, like a CT scan, but it can also show slices from several different angles. The patient may sometimes be injected with a contrast agent before the scan. MRIs can produce very detailed images of the prostate and show both local lesions and whether the cancer has spread outside of it to the seminal vesicles or nearby organs like the bladder.
- Ultrasound exam . Ultrasound uses high-frequency sound waves and their echoes to produce a picture of internal organs or masses on a computer screen. The test is painless and does not expose the patient to ionizing radiation. Ultrasound exams can be useful in determining local spread of cancer, but they can't always detect if cancer has penetrated into the capsule or to the seminal vesicles.
- Contrast ultrasound exam. (Note: Contrast ultrasound is approved and used in Europe but is not approved for use in the US.) Standard (gray-scale) ultrasound can only detect about half of cancerous lesions in the prostate, and it is not good at distinguishing between nonmalignant lesions and cancerous ones. In contrast ultrasound, a microbubble contrast agent is injected. Cancer tumors have more microscopic blood vessels than normal tissue does. The microbubbles pass through these densely packed vessels, which appear as bright areas in the ultrasound image.
- Computed tomography (CT) . A CT scan, also known as a CAT scan, uses X-rays to produce multiple images of the body. A computer then combines these images into cross-sectional "slices" or 3-dimensional volumes, which can be studied to see if cancer is present. Before a CT scan, the patient may drink a contrast liquid and/or be injected with a different type of contrast. These help to outline parts of the body in the images. CT scans can help show whether cancer has spread to nearby lymph nodes and other pelvic areas, but they rarely provide useful information about newly diagnosed cancers that are likely to be confined to the prostate gland, based on other findings.
- Positron emission tomography/CT (PET/CT) . Using traces of radioactive agents, PET scans detect a metabolic clue that cancer cells are growing actively. CT scans use X-rays to provide detailed images of anatomical structures. Fusing the two together in a PET/CT scan provides more information than do the two separately. PET/CT scans can detect cancer spread by identifying changes that are happening at a functional and cellular level.
- Single-photon emission computer tomography (SPECT) with ProstaScint. These scans are used to evaluate patients at high risk of lymph node metastases in the pelvic region and patients with rising PSA after prostate surgery who are at risk of hidden metastasis.
Diagnosing Prostate Cancer (VIDEO)
Treating Prostate Cancer (VIDEO)
What Is Prostate Cancer?
Screening and Detection
Growth and Spread of Cancer
Related Health Centers:
Breast Cancer, Cancer Introduction, Colorectal Cancer, Prostate Cancer