Dr. Oliver Sartor, the Laborde Professor of Cancer Research in the Medicine and Urology Departments of the Tulane School of Medicine, is one of the leading researchers in advanced prostate cancer today. He is also the Editor-in-chief of Clinical Genitourinary Cancer and the author of more than 100 scientific papers.
Prostatepedia spoke with Dr. Sartor about recurrent prostate cancer.
How do we know a man’s cancer has started growing again after treatment?
Dr. Sartor: We have two basic algorithms. The first is for radical prostatectomy. A man with no prostate should have no PSA. If you don’t have a prostate, your PSA ought to be undetectably low, because there is only one source of PSA—the prostate or prostate cancer. When you have any PSA after radical prostatectomy, it is presumptive evidence of prostate tissue.
There are various guidelines for recurrence. If you have a consistent rise in PSA at any level after an initially undetectable PSA, that is considered recurrence. Currently, I’m treating somebody with a 0.05 PSA with radiation therapy, because I believe that he has a recurrence. His PSA was undetectable and then went from 0.01to0.02 to 0.03 to 0.04 to 0.05.
It is also possible for men to have a detectable PSA after radical prostatectomy that, on occasion, is not due to cancer. This is called a benign margin and is rarely discussed, but it is present in about 10% of people if you look carefully at the pathology. A benign margin occurs because during surgery the surgeon can cut into the prostate, and particularly down around the apex, but still leave behind a little bit of prostate tissue. If that happens and there are benign prostate retentions post-surgery, you definitely will have a very low PSA that just sits there—doesn’t grow, doesn’t move.
Extremely rarely, you can have fluctuations so that the PSA goes up and down for reasons we don’t understand. I have had that happen to people in my practice.
But the bottom line is that we start thinking about recurrent cancer when the PSA is detectable after surgery because there has to be an explanation. You don’t just have PSA after surgery without an explanation. Every PSA needs to be explained.