New research published in Mayo Clinic Proceedings illustrates that repeating initially elevated prostate-specific antigen (PSA) results could resolve whether a patient is at high risk for prostate cancer, and avoid more costly biopsies.
Studies in clinical literature have recently questioned the validity of PSA tests as a screening mechanism for early detection of prostate cancer. Screening for this disease can be beneficial, yet infections, physical activity, and laboratory error can all lead to variability in PSA levels, explained study author Rodney Breau, MD, a prostate cancer surgeon and associate scientist in epidemiology at The Ottawa Hospital and the University of Ottawa, in a statement issued by the Ottawa Hospital Research Institute.
Recent CLN Stat articles have addressed the potential shortcomings of PSA tests. One article highlighted a study by Indian researchers, who concluded that variability among PSA assays might increase risk of misdiagnosing biochemical failure in prostate cancer patients. In another article, Swedish researchers indicated that PSA tests were limited in that they couldn’t adequately distinguish between benign and more aggressive cancer, and pointed to a multi-input model known as the STHLM3 blood test as a more effective tool for detecting aggressive cancer at the early stages.
Some task forces have called for PSA testing to be abandoned, claiming it leads to unnecessary biopsies, according to the statement from the Ottawa Hospital Research Institute.
To address the problems with PSA fluctuation, Breau said he and his fellow researchers “implemented a protocol to always repeat an abnormal test before referring a patient for a biopsy. We had a hunch that this would reduce unnecessary biopsies and our study shows that our suspicion was correct.”
Researchers enlisted 1,268 patients with high or abnormal PSA levels between 4 and 10 ng/mL, who were referred to the Ottawa Regional Prostate Cancer Assessment Clinic from the spring of 2008 to the spring of 2013. “Univariate and multivariate associations between a normal result on repeated PSA testing and the risk of prostate biopsy, cancer diagnosis, and Gleason score of 7 or higher were examined,” the authors indicated in their summary of the results.
Of the 953 patients who had two abnormal PSA test results, 62.3% underwent a biopsy. This compares with 315 patients (25% of the test subjects) whose second PSA test result came back normal. Among this group, just 28.3% had a biopsy—representing a 55% reduction in biopsies from the group of patients who had abnormal repeated tests.
The fact that 19% of the men with repeated abnormal tests were diagnosed with cancer within a year, versus just 3% who had conflicting results, underscores the importance of administering a second PSA test, the researchers noted.
They concluded that “routinely repeating a PSA test in patients with an elevated PSA level is independently associated with decreased risk of prostate biopsy and prostate cancer diagnosis.” Before opting for a costly biopsy, they advised that men with abnormal PSA levels first get a second PSA test.
“Some doctors and patients may be worried about missing a significant cancer diagnosis if they forgo a biopsy after conflicting test results, but our study shows this is very unlikely,” Breau said. “It is also important to remember that the PSA test is just one factor we evaluate when deciding to do a biopsy, and these decisions are always made together with the patient, and can be revisited if risk factors change.”