Less than 2 mm of Gleason pattern 4 carried risks similar to favourable intermediate-risk disease

Design

Retrospective cohort of men with MRI-targeted and systematic biopsy followed by radical prostatectomy

Population

2,499 men with grade group 2 to 4 prostate cancer

Primary outcome

Adverse pathology at prostatectomy and 5-year biochemical recurrence by total GP4 length

Effect

Under 2 mm GP4: adverse pathology 5.2% vs 5.0% and 5-year BCR 20% vs 21% for favourable intermediate-risk

This study looked at 2,499 men with grade group 2 to 4 prostate cancer on MRI-targeted and systematic biopsy who went on to radical prostatectomy. The authors measured total length of Gleason pattern 4 (GP4), adding the millimetres in systematic cores to the average across targeted cores.

Of men in grade groups 2, 3 and 4, 73%, 19% and 15% respectively had less than 2 mm of GP4. Men with under 2 mm of GP4, whatever the grade group, had adverse pathology in 5.2% against 5.0% and 5-year biochemical recurrence in 20% against 21%, matching men with favourable intermediate-risk disease. Using under 2 mm as a surveillance cut-off would roughly double the number classed as eligible for active surveillance.

The authors say the best way to measure GP4 and the right cut-point still need to be defined before clinical use. The men all had surgery, so those chosen for surveillance may differ.

• Ask your pathologist to report the total length of Gleason pattern 4 in millimetres.
• Do not use a 2 mm threshold for surveillance outside a research or protocolised setting yet.
• Discuss active surveillance for selected grade group 2 disease according to current guidelines.
• Remember that 20% had biochemical recurrence at 5 years even in the low-GP4 group, in men treated surgically.
• Include MRI findings and PSA density in the same discussion.

Why it matters

Current risk groups lump together men with very small and very large amounts of pattern 4.

Don't overread it

A retrospective surgical cohort; it does not show that men with under 2 mm are safe on surveillance, and the guidelines have not changed.

The statistics, in plain English

Similar risks between groups means the same percentages were seen, not that the groups are the same men. Recurrence after surgery is a surrogate for outcomes under surveillance, where men are treated only if disease progresses.

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