SAN FRANCISCO—Prostatitis can cause serum PSA levels to shoot up, a finding that needs to be taken into account when using PSA velocity for prostate cancer detection, according to data presented here at the Prostate Cancer Symposium.
In a study of 1,851 men, those with a modest rise in PSA of less than 2.0 ng/mL per year had a significantly increased risk of prostate cancer, said E. Scott Eggener, MD, a urologic oncology fellow at Memorial Sloan-Kettering Cancer Center.
But men with a PSA velocity of 4.0 ng/mL per year or higher were just as likely to have prostatitis as they were to have prostate cancer, said Dr. Eggener, who performed the study with William J. Catalona, MD, Professor of Urology at Northwestern University Fienberg School of Medicine.
Speaking at the symposium, a meeting cosponsored by ASCO, ASTRO, the Prostate Cancer Foundation, and the Society of Urologic Oncology, Dr. Eggener said that after the initial rapid rise in PSA, men with prostatitis will often have a significant drop in PSA in the year or two following biopsy.
Men with a normal digital rectal exam, elevated PSA, and high PSA velocity should have a repeat PSA to confirm the elevated value, he said, and any symptoms or laboratory findings suggestive of prostatitis should prompt an appropriate evaluation and consideration of treatment.
Community-Based Screening Trial
The study included 1,851 men enrolled in a community-based prostate cancer screening trial who had a non-suspicious digital rectal examination and a calculable PSA velocity, and had undergone their first prostate biopsy between 1989 and 2000. Most of the men underwent quadrant or sextant transrectal ultrasound-guided prostate biopsies, Dr. Eggener noted.
Of the total, 468 (25%) were diagnosed with prostate cancer, and 135 (7%) were diagnosed with prostatitis on their first biopsy.
The mean PSA velocity of the men with cancer was 1.5 ng/mL per year. In contrast, the mean PSA velocity for the men with prostatitis was 2.7 ng/mL per year.
In the year following biopsy, the mean PSA velocity among the men with prostatitis fell 1.6 ng/ML; in the two years after biopsy, it dropped 0.7 ng/mL.
When the researchers analyzed the ranges of PSA velocity and the probability of prostate cancer during the following two years, men with PSA velocities of 0.3 to 0.5 ng/mL per year in the year before biopsy were found to be most likely to have cancer. Men with PSA velocities of 2.0 ng/mL per year or more, on the other hand, were at greater risk of prostatitis.
In the group of men who had a PSA velocity below 2.0 ng/mL in the year before biopsy, 30% had prostate cancer on their first biopsy and 5% had prostatitis. In the men with a PSA velocity of 4.0 ng/mL per year or higher, 13% had cancer on their first biopsy and 13% had prostatitis.
Prostatitis-associated PSA rises are not a rare occurrence, Dr. Eggener said, with about 15% of the men in the study having high PSA velocities due to the condition.
PSA Velocity Still Useful
That said, he and others agreed that there is still a place for PSA velocity in cancer diagnosis.
“This is a potential confounding factor we need to be aware of. It does not mean PSA is dead,” Dr. Eggener said.
“A PSA rise is like a smoke alarm in the home. It warrants attention but doesn't mean that something is dramatically wrong.”
“If it jumps dramatically, you should look to see if symptoms or urinalysis suggest infection. If infection is present, treat it as an infection and repeat the PSA.”
“If there is nothing to suggest infection, we still recommend a repeat PSA to confirm the value. If it remains elevated, a biopsy to rule out cancer is warranted,” he said.
Paul H. Lange, MD, Professor and Chair of the Department of Urology at the University of Washington, said that the results “reinforce what many of us in the trenches already know—PSA velocities are an art.”
“This paper is a warning. Plenty of things can make PSA rise. It could be prostatitis or benign prostatic hyperplasia, and we're still looking at a variety of other factors.”
But when interpreted by “someone who knows what's going on, the rate of rise still gives us a clue as to whether there is cancer.”