SAN FRANCISCO — Prostatitis can quickly lead to surges in prostate-specific antigen levels, potentially undermining the use of the biomarker's rate of change to help detect cancer, Dr. Scott Eggener said at a symposium on prostate cancer sponsored by the American Society of Clinical Oncology.
Previous studies have shown that prostate-specific antigen (PSA) velocity can be a valuable tool for assessing prostate cancer risk. Specifically, PSA velocity elevations of 2.0 ng/mL per year or higher have been identified as significant with respect to the risk of dying of prostate cancer, said Dr. Eggener of Memorial Sloan-Kettering Cancer Center in New York. It has also been suggested, however, that certain conditions, such as prostatitis and benign prostatic hyperplasia, could be confounding variables for rising PSA velocities.
Dr. Eggener and his colleagues analyzed records from 1,851 men enrolled in a community-based prostate cancer screening trial. At the time of their first biopsy, 468 men were diagnosed with prostate cancer, and 135 were diagnosed with prostatitis.
All of the men had a normal digital rectal exam and a calculable PSA velocity for the year prior to biopsy.
“What we found, relative to rising PSA velocity, was a general trend for decreasing cancer detection rate and a corresponding trend for increasing prostatitis,” Dr. Eggener said at the symposium, which was cosponsored by the Society of Urologic Oncology and the American Society for Therapeutic Radiology and Oncology.
Specifically, 30% of the men with a PSA velocity of 0–1.99 ng/mL in the year before biopsy had prostate cancer, and 5% had prostatitis. In comparison, among men with a PSA velocity of 2.0–3.99 ng/mL, 22% had cancer on first biopsy, and 8% had prostatitis.
Men whose PSA velocities were greater than 4.0 ng/mL were equally likely to have prostatitis or prostate cancer, with 13% being diagnosed with each condition.
The risk of cancer diagnosis peaked relative to PSA velocity increases of 0.3–0.5 ng/mL per year, and the risk of prostatitis diagnosis rose substantially with PSA velocity increases of more than 2.0 ng/mL per year, Dr. Eggener said.
“Men with prostatitis often have dramatic rises in PSA prompting biopsy, but subsequently have a significant drop in PSA in the year or two following biopsy,” he said.
Men with a normal digital rectal exam, elevated PSA, and a high PSA velocity should therefore undergo repeat PSA testing. “If any symptoms or laboratory findings suggest prostatitis, they should undergo appropriate evaluation and treatment,” he said.
Dr. Eggener stressed that PSA velocity continues to be “very useful in assessing prostate cancer risk,” but that dramatic increases over short periods of time should raise suspicion of prostatitis, in addition to prostate cancer.
