PSA levels varied among participants receiving annual testing
Patients with a prostate-specific antigen (PSA) level above a given biopsy threshold and no recent PSA test results below that threshold could proceed to further diagnostic evaluation without repeat testing, authors of a recent study suggested.
Intra-individual variation in prostate-specific antigen (PSA) levels is common in men undergoing annual testing, a recent study found.
Researchers used data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial to evaluate yearly PSA variability and implications of repeating PSA testing after an elevated PSA level. The study included men ages 54 to 75 years who were participating in the PLCO's screening arm and received PSA testing annually over six years (between 1995 and 2006) without a prostate cancer diagnosis. The primary outcome was the proportion of PSA measurements above one of three biopsy thresholds of interest (2.5, 3.0, and 4.0 ng/mL) that decreased below that threshold at subsequent yearly measurement. The results were published Sept. 18 by JAMA Oncology.
The study included 11,176 patients with a median age of 60 years. Of these, 2,700 had a PSA threshold of 2.5 ng/mL, 1,928 had a PSA threshold of 3.0 ng/mL, and 952 had a PSA threshold of 4.0 ng/mL at least once. Among PSA measurements greater than or equal to 2.5 ng/mL, 22% (95% CI, 21% to 23%) decreased below 2.5 ng/mL the following year, with similar rates for the 3.0 ng/mL and 4.0 ng/mL thresholds (25% [95% CI, 24% to 27%] and 30% [95% CI, 27% to 32%], respectively). Fifty-four percent (95% CI, 53% to 56%) of men who had at least one PSA level greater than or equal to 2.5 ng/mL had a subsequent level below this threshold, with slightly greater rates for the higher thresholds (58% [95% CI, 56% to 60%] and 62% [95% CI, 59% to 65%], respectively). In a predictive scoring system that incorporated current and prior PSA levels, patients with PSA levels that were persistently above the thresholds had a less than 10% probability of levels decreasing below the thresholds.
The researchers noted that their findings are based on annual PSA measurements among men without prostate cancer, among other limitations. “These findings support guideline recommendations to confirm elevated PSA results in most patients,” the authors wrote. “Patients with a prior PSA above a biopsy threshold, and no PSAs below that threshold within the recent preceding several years, could proceed to further diagnostic evaluation without repeat testing. Further research is needed to establish the optimal timing for repeat testing.”