Metastatic prostate cancer risk low in older men nearing age limit for PSA screening

Older men who have had prostate-specific antigen (PSA) testing and are approaching the age limit for recommended screening appear to have a relatively low risk of developing metastatic or fatal prostate cancer, suggests a recent study.

A random sample of patients in the US Veterans Health Administration was used to identify 80,706 men who had received PSA testing between 70 and 75 years of age. The primary endpoint was time to development of either metastatic prostate cancer or death from prostate cancer.

The investigators accounted for competing events (ie, death from nonprostate cancer causes) in evaluating the discriminative ability of PSA as well as for positive and negative predictive values at three time points using cumulative/dynamic modelling.

PSA showed time-dependent discrimination, with receiver operating characteristic area under the curve decreasing from 0.83 at 5 years to 0.77 at 10 years and 0.73 at 14 years. No statistically significant difference was noted when stratifying by race.

At PSA thresholds between 1 and 8 ng/mL, the positive predictive value of developing advanced prostate cancer was significantly higher in Black than White patients. For example, White men had a 2.4-percent risk of an event at a PSA >3 at 5 years, 2.9-percent at 10 years, and 3.7-percent at 14 years. On the other hand, Black men had 4.3-percent, 6.5-percent, and 8.3-percent risk, respectively.

“In men aged 70 to 75 years deciding whether to cease PSA testing with borderline-elevated PSA values, the risk of developing metastatic or fatal prostate cancer is quantifiable and relatively low,” the investigators said. “Risk assessment in this setting must account for the higher incidence of prostate cancer in Black men.”