5-alpha reductase inhibitors on active surveillance linked to less grade progression

Design

Single-institution retrospective cohort

Population

1,938 men with Grade Group 1 prostate cancer on active surveillance

Primary outcome

Grade progression, outlet procedure and definitive treatment

Effect

5-ARI per year: grade progression HR 0.80 (0.72 to 0.89); definitive treatment HR 0.53 (0.41 to 0.67)

This retrospective study, published in June 2026, reviewed 1,938 men with Grade Group 1 prostate cancer on active surveillance at one institution. It examined prostate volume at confirmatory biopsy and 5-alpha reductase inhibitor use against grade progression, outlet procedures and definitive treatment.

Each additional 10 cc of prostate volume was associated with less grade progression (HR 0.89, 95% CI 0.85 to 0.93) and less definitive treatment (HR 0.91, 0.88 to 0.95). Each year of 5-alpha reductase inhibitor use was associated with less progression to Grade Group 2 or higher (HR 0.80, 0.72 to 0.89), to Grade Group 3 or higher (HR 0.84, 0.73 to 0.97), and less definitive treatment (HR 0.53, 0.41 to 0.67). Men with glands over 80 cc more often needed an outlet procedure.

Men on surveillance often have lower urinary tract symptoms, and some clinicians avoid 5-alpha reductase inhibitors because they lower PSA and might obscure progression. This cohort found no sign of harm and an association with less progression. It cannot show the drugs prevent progression, but it supports using them when symptoms warrant, with PSA interpreted accordingly.

• Treat lower urinary tract symptoms during active surveillance as you would otherwise, including with 5-alpha reductase inhibitors.
• Record a new PSA baseline about six months after starting a 5-alpha reductase inhibitor.
• Investigate any rise in PSA from the new nadir on a 5-alpha reductase inhibitor.
• Continue scheduled MRI and biopsy surveillance regardless of PSA on these drugs.
• Do not start a 5-alpha reductase inhibitor solely to slow cancer progression on this evidence.

Why it matters

A worry that has kept symptomatic men on surveillance off an effective treatment is not borne out here.

Don't overread it

This retrospective association cannot show that 5-alpha reductase inhibitors prevent progression.

The statistics, in plain English

A hazard ratio of 0.80 per year of use means about 20% lower rate of grade progression for each year on the drug. Because men were not randomised, those prescribed the drug may differ in ways that also affect progression, and the drug's effect on gland size and PSA can change how often biopsy is triggered.

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