Despite recent claims by some urologists that measuring the blood proteinprostate-specific antigen (PSA) may not be effective in predicting risk ofprostate cancer, a Johns Hopkins study of more than 2,000 men confirms thatPSA remains the best measure of the likelihood of cancer recurrence aftersurgery.
Results of the study, published in the October issue of The Journal ofUrology, demonstrated that men with high PSA levels prior to prostateremoval surgery were significantly more likely to have advanced clinicalstages of cancer, evidence of higher grade cancers in surgically removedtissue, and spread of cancer cells beyond the prostate. In addition,increasing PSA was significantly associated with increased risk of cancerrecurrence after surgery, even in men with lower PSA levels prior to surgery.
The study was led by Stephen J. Freedland, M.D., clinical instructor ofurology, and Alan W. Partin, M.D., Ph.D., professor and chair of urology atJohns Hopkins' Brady Urological Institute.
"In our study, PSA levels measured before prostate removal surgery weresignificantly associated with the risk of recurrent cancer after surgery,"Freedland says. "These data support the notion that PSA remains the bestavailable prostate cancer tumor marker. It certainly suggests that the PSAera is alive and well."
PSA is a protein produced by cells of the prostate gland. Prostate cancercan increase PSA, so the higher the PSA level, the greater the likelihoodthat a patient has prostate cancer. Also, higher PSA values generallyreflect larger, more aggressive cancers. Freedland acknowledges thatbecause PSA provides physicians with a measure of a patient's prostatehealth at a single point in time, it's "far from perfect." However, hesays, "it's better than anything else we have."
"As a screening tool, PSA has done what we wanted it to do," Freedlandsays. "It detects advanced disease early and reduces the likelihood ofmetastatic disease."
For the study, Freedland and colleagues reviewed patient records for 2,312men who had prostate removal surgery at Johns Hopkins between 1992 and2004. All operations were performed by Patrick C. Walsh, M.D., professorand former chair of urology. The research team compared the associationbetween preoperative PSA and the risk of cancer recurrence after surgery.
During an average follow-up of five years, 211 men (10 percent) had signsof recurrent cancer. Higher PSA levels prior to surgery were significantlyassociated with increased risk of cancer after surgery. Compared to menwith PSA levels less than 10 nanograms per milliliter, men with PSA valuesbetween 10 and 19.9 nanograms per milliliter were more than three timesmore likely to develop cancer after surgery. Men with PSA levels of 20nanograms per milliliter or greater were more than five times more likelyto develop cancer after surgery than those with low PSA levels.
Even in men with PSA values of less than 10 nanograms per milliliter,increasing PSA was significantly associated with increased risk of cancerafter surgery. For each two-point increase in PSA, the risk of cancer aftersurgery approximately doubled.
"From our study and others, it is clear that a single PSA value is anextremely useful measure of a patient's risk of progression after surgery,"Freedland says. "However, looking at how quickly the PSA increases overtime is likely to be even more informative than a single value."
The study was supported by the National Institutes of Health, theDepartment of Defense and the American Foundation for UrologicalDisease/American Urological Association.
Coauthors were Leslie A. Mangold and Walsh.
Brady Urological Institute at Johns Hopkins: http://urology.jhu.edu/
American Urological Association: http://www.auanet.org
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