Use of 5-alpha-reductase inhibitors (5-ARIs) does not increase the risk of dying from prostate cancer, investigators of a Swedish population-based study reported at the American Urological Association’s 2022 annual meeting in New Orleans, Louisiana.

“The disparate results of randomized control trials and observational studies regarding the development and mortality of prostate cancer in men exposed to 5-ARIs have caused hesitancy in prescribing the drug,” lead researcher Lars Bjornebo, MSC, MD-PhD candidate at Karolinska Institute, Solna, Sweden, explained in an interview. “We hope that our research will alleviate these concerns and that men with lower urinary tract symptoms caused by benign prostate hyperplasia can get better access to 5-ARIs without worrying about an increased risk for prostate cancer.”

Among 349,152 Swedish men who had a PSA test, 26,190 became new users of the 5-ARI drugs finasteride or dutasteride. The median exposure to 5-ARIs was 4.5 years. Over a median 7.6 years of follow-up, 35,767 men died, including 852 from prostate cancer.

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In adjusted multivariable analyses, the risk for prostate cancer mortality significantly decreased by 52% with 6-8 years and more than 8 years of 5-ARI exposure, Bjornebo reported. Less than 6 years of 5-ARI use was not associated with survival.

The investigators noted that men taking vs not taking 5-ARIs had more PSA tests (median 0.63 vs 0.33) and prostate biopsies (median 0.22 vs 0.12) per year. “The intensity of prostate cancer testing could affect outcomes of prostate cancer diagnosis and death from prostate cancer,” according to Bjornebo.

A 2019 study of US veterans published in JAMA Internal Medicine found that prediagnostic use of 5-ARIs was associated with delayed diagnosis and worse cancer-specific outcomes, including death, in men with prostate cancer. The US study only considered men with a prostate cancer diagnosis. The Swedish study examined men without prostate cancer at study entry, which is better suited for studying mortality, according to Bjornebo.

“More research on how 5-ARIs affect the sensitivity and specificity of diagnostic tests such as PSA, prostate biopsies, and MRIs would be valuable.”


Björnebo L, Nordström T, Discacciati A, et al. Long-term effects of 5-alpha-reductase inhibitors on prostate cancer mortality – a large population-based prospective study. Presented at: AUA 2022; May 13-16, 2022, New Orleans, Louisiana. Abstract PD03-02.