Study findings suggest a need for increased awareness of prostate-specific antigen (PSA) suppression induced by the use of 5α-reductase inhibitors (5-ARIs) among older adults with prostate cancer (JAMA Netw Open. 2019;2[10]:e1913612).

“Our group has recently published that among US military veterans, 5-ARIs are associated with delays in prostate cancer…diagnoses, higher grade and stage at presentation, and worse PC [prostate cancer]-specific mortality…presumably because of misinterpreted PSA values,” explained Abhishek Kumar, MAS, Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, and colleagues.

Based on the hypothesis that these results are generalizable to the broader population, Mr Kumar et al conducted a cohort study using the Strengthening the Reporting of Observational Studies in Epidemiology reporting guideline.

Data for patients with stage I to IV prostate cancer and known PSA levels at diagnosis between January 1, 2008, and December 31, 2013, were included in the study if they had no missing covariate information and Medicare Part D coverage. Information was collected using the SEER Program–Medicare linked database and analyzed between February 1, 2019, and April 30, 2019.

Follow-up lasted until death or December 31, 2015, for all patients.

Ultimately, a total of 30,313 patients with a median follow-up of 3.75 years were included in the analysis. Of these patients, 2373 (7.83%) were prescribed 5-ARIs at least 6 months before being diagnosed with prostate cancer and had a median treatment duration of 2.46 years.

The 4-year rates of cumulative incidence of death from prostate cancer were 5.3% and 2.8% in those given and not given 5-ARIs.

Of note, those who did receive 5-ARIs were more likely to present with high grade disease than those who did not receive 5-ARIs (29% vs 18%, respectively; difference, 12%; 95% CI, 9%-13%; P <.001); similar results were observed for those with high risk (38% vs 28%, respectively; difference, 9%; 95% CI, 8%-11%; P <.001), clinically node positive (3% vs 2%, respectively; difference, 1%; 95% CI, 0.6%-2%; P <.001), and clinically metastatic (3% vs 2%, respectively; difference, 1%; 95% CI, 0.5%-2%; P <.001) disease.

Mr Kumar and colleagues also noted that, at diagnosis, the median adjusted PSA level was significantly higher in 5-ARI users versus nonusers (14.2 ng/mL vs 6.6 ng/mL, respectively; difference, 7.6 ng/mL; 95% CI, 7.0-8.2 ng/mL; P <.001).

“Our results suggest a need for increased awareness of 5-ARI–induced PSA suppression…and systems-based mechanisms to help improve care for men using 5-ARIs,” they concluded.—Hina Porcelli