Situations Where PSA is Misleading
PSA is a powerful blood test for detecting a cancer relapse. However, there is always a danger of misinterpretation.
PSA Rise after Surgery
A small chunk of benign gland is sometimes left behind after surgery. In such cases, PSA may hover indefinitely in the 0.1 to 0.3 range, even when no cancer is present. When evaluating a man with low levels of detectable PSA, the original Stage of Blue should be considered. If it was Sky, then benign prostate gland cells are a more likely explanation. In this scenario, PSA should be monitored to determine if there is an upward trend or not. Sequential scans to determine if a small nodule is present and growing may provide some additional information. PSA levels that don’t rise and nodules that don’t enlarge are more likely to be from persistent, noncancerous residual prostate tissue.
PSA Rise after Radiation
Noncancerous PSA elevations after radiation occur frequently, particularly after seeds. The “PSA bounce” is thought to result from radiation-induced inflammation of the prostate gland. A cancer relapse can be distinguished from a bounce by examining sequential PSA levels. A smooth upward progression is typical of a cancer relapse. With a bounce, levels tend to oscillate up and down in a zigzag pattern. Another factor to be considered is the original Stage of Blue because relapses after Azure are more common. Other factors that influence PSA levels after radiation and are the size of the prostate gland and the testosterone level. Clearly, interpreting PSA levels after radiation requires oversight by a physician experienced with the treatment of prostate cancer.
ABOUT THE AUTHOR
Mark Scholz, MD is the Executive Director of the Prostate Cancer Research Institute. He is also the Medical Director of Prostate Oncology Specialists Inc. He received his medical degree from Creighton University in Omaha, NE. Dr. Scholz completed his Internal Medicine internship and Medical Oncology fellowship at University of Southern California Medical Center. He is co-author of Invasion of the Prostate Snatchers. He has authored over 20 scientific publications related to the treatment of prostate cancer.