Johns Hopkins Health Alert
Imaging Studies for Prostate Cancer: What to Expect
Determining the extent of prostate cancer is important for predicting the course of the disease and in choosing the best treatment. Depending on the Gleason score and the initial PSA results, your physician may order imaging studies to determine whether the prostate cancer has spread to distant sites.
Some men will need to undergo a bone scan to determine whether their prostate cancer has spread to the bones. The bone scan involves intravenous injection of a radioactive substance that is preferentially taken up by the damaged bone. A special scanner is then used to detect the radioactivity. Areas of the body that show increased radioactivity have bone damage, possibly because cancer has spread to the bone.
Some physicians do not order a bone scan when PSA levels are less than 10 ng/mL because the likelihood of cancer spread is very low. Others prefer to order a scan, even if the risk of spread is low, to obtain a baseline measurement for comparison if a bone scan is needed at a later date. Men who have a PSA level of 20 ng/mL or higher, a Gleason score of 8 to 10 or disease extensive enough to be felt on both sides of the prostate or beyond the prostate should have a bone scan.
The ProstaScint scan may be used to look for prostate cancer cells that have spread to the lymph nodes or soft organs. ProstaScint uses antibodies that attach to a protein called prostate-specific membrane antigen on prostate cancer cells. These antibodies mark cancer cells with a radioactive isotope that is then picked up by a special scanner. The ProstaScint scan is not considered very accurate. It is usually used when PSA levels start to rise again after surgery or radiation therapy.
What’s next: If the digital rectal exam, PSA and Gleason score suggest that the cancer has spread, computed tomography (CT) or magnetic resonance imaging (MRI) may be performed to look for enlarged lymph nodes. In some instances, the urologist may recommend a laparoscopic biopsy. In this procedure, a surgeon uses a laparoscope (an instrument with a tiny light and camera) to view the lymph nodes near the prostate and take samples to check for cancer.
New approaches for detecting the presence or progression of prostate cancer are being investigated. These include positron emission tomography (PET) and PET/CT. Further development of these imaging procedures may provide more precise ways to diagnose recurrences and locate metastases.
Posted in Prostate Disorders on October 20, 2011
Medical Disclaimer: This information is not intended to substitute for the advice of a physician. Click here for additional information: Johns Hopkins Health Alerts Disclaimer
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