Surprising Findings about PSA and Prostate Cancer
May 24, 2000
It is well accepted by urologists that the higher a man's blood level of prostate specific antigen (PSA) prior to treatment for prostate cancer, the worse the prognosis for cure. But new data presented at the annual meeting of the American Urological Association in Atlanta early this month challenges this common wisdom.
"Serum PSA drawn preoperatively does not reflect a change in cure rate until the level reaches nine ng/ml. The cure rates by radical prostatectomy are all the same between two and nine ng/ml," stated Dr. Thomas A. Stanley of Stanford University in Palo Alto, California. He presented his data and conclusions to fellow urologists in a special lecture at the meetings.
Dr. Stanley looked at long-term data from 695 men with prostate cancer. As expected, among men with preoperative PSA levels above 10 ng/ml, higher PSA levels predicted lower cure rates. But he looked specifically at those men whose PSA levels were between two and nine ng/ml. His surprising findings: the cure rate was about 80 percent across the whole range.
"PSA is a very good marker above nine ng/ml," stated Dr. Stanley. "But something else is driving PSA other than the cancer between two and nine". And that something else, he reasons, is benign prostate enlargement.
"I believe our diagnosis of prostate cancer in men with a PSA between two and nine ng/ml is pure serendipity, unrelated to morphologic variables of the cancer or to its cure rate," says Dr. Stanley. It is well known that benign prostatic hyperplasia (BPH), a non-cancerous condition, also elevates PSA. The researcher noted that among men with prostate cancer, PSA levels did not reflect either cancer stage or size of the tumor.
"The bottom line is that we urgently need a far better marker for prostate cancer than PSA," Dr. Stanley concluded.
If the findings are supported by more research, the clinical approach to treating men with prostate cancer could change: men with lower PSA levels might be told to delay surgery "because the chance of cure should be about 80 percent until PSA crosses the nine ng/ml threshold," he stated.
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Cytogen PMSA is looking to be the breakthrough marker.
Jim |
