Last Modified: July 30, 2006
Dear OncoLink "Ask The Experts,"
What is Prostascint®?
Carolyn Vachani RN, MSN, AOCN, OncoLink's Nurse Educator, responds:
Prostascint® is a radio-labeled monoclonal antibody, which is a type of medication that targets specific cells. In the case of Prostascint®, the antibody targets Prostate Specific Membrane Antigen (PSMA), a protein expressed by prostate tissue. Attached to the antibody is a radioactive substance that can be detected with a special nuclear medicine scan (SPECT). The antibody is taken up by prostate cancer cells, allowing them to be visualized on the scan.
This test may be helpful to determine the course of treatment for a patient who is post-prostatectomy and has suspected metastasis (spread of the disease). It may also be helpful in conjunction with other scans (CT or MRI) for higher risk patients, by detecting lymph nodes in the abdomen that are involved with prostate cancer cells, but may still appear falsely normal on CT or MRI scans.
The test does not detect bone metastases very well, and so a bone scan should be done if bone metastases are suspected. The antibody is taken up by normal prostate tissue, thus it is not very useful in detecting inter-prostate lesions in patients who have not had a prostatectomy. Radiologists must be trained in order to provide reliable readings of Prostascint scans.
The procedure is as follows: the patient is given an intravenous (IV) infusion of the monoclonal antibody, and 30 minutes later, a scan is performed. The patient is then sent home and told to drink plenty of fluids for the next few days. A second scan is done between 96 and 120 hours (4-5 days) after the infusion. The night before this scan, the patient must complete a bowel prep, which cleanses the bowel of any stool, making the scan easier to interpret. The first scan (on the day of the infusion) takes approximately 1 hour, while the second scan takes approximately 2 ½ hours.