The Prostascint scan is a relatively new addition to the numerous tests that can be used to detect the spread of prostate cancer to other parts of the body.
Why Was the Prostascint Scan Developed?
The Prostascint scan was developed in order to help doctors detect the spread of prostate cancer to other parts of the body, particularly the lymph nodes.
Detecting cancerous spread to the lymph nodes can significantly change the optimal treatment. Failure to find cancer that exists in the lymph nodes can result in prostate cancer in areas distant from the prostate going untreated.
How Does the Prostascint scan work?
The Prostascint scan makes use of radioactively tagged antibodies (specifically Indium-111 labeled capromab pendetide) that are designed to travel throughout the body and attach themselves to prostate cancer cells. If prostate cancer cells have invaded lymph nodes in the pelvis or elsewhere in the body, then the antibodies typically will find them and bind to them.
Because they are tagged with tiny amounts of radioactivity, the antibodies' locations can be detected using a special machine called a gamma camera. If a lot of the antibodies congregate in the same site in the body, then the picture of the body that the gamma camera produces will show this site as a "hot spot" of radioactivity.
Areas that are "hot" may be lymph nodes that are involved by prostate cancer.
It is also important to note that not all hospitals offer the Prostascint scan and not all doctors that treat prostate cancer believe that the test is that useful or reliable.
What to Expect From the Prostascint Scan
The Prostascint scan is a two step test spanning 4 days.
On the first day, you will go to the hospital to receive an injection into your vein of the radioactively tagged antibodies.
Four days later, you will be asked to return to the hospital for the imaging portion of the test. The night before this portion of the exam, you will likely be asked to take laxative or use an enema to cleanse your bowel and make the test easier to interpret.
To be imaged, you will be situated next to the gamma camera (which is a very large machine) for about 45 minutes.
During this period, a small sample of blood will be taken, mixed with more radioactively tagged antibodies, and then re-injected into your body. You will then move to another, different camera for a final hour of imaging.
The whole process on the second day at the hospital will take about two hours.
A fair percentage of patients also will need to return the next day for additional imaging.
Is the Radioactivity Dangerous?
It is thought that the tiny amount of radioactivity associated with the injected antibodies is too small to cause any harm to the patient.
Klein EA. Management of Prostate Cancer. 2nd edition. 2004.
Schettino CJ, Kamer EL, Noz ME, et al. Impact of fusion of indium-111 capromab pendetide volume data sets with those from MRI or CT in patients with recurrent prostate cancer. AJR. 2004; 183:519-524.