PSA density below 0.10 after a negative MRI marked a lower long-term cancer risk

Design

Pre-specified analysis of a population-based randomised screening trial (Göteborg-2)

Population

1685 men with a negative initial prostate MRI (PI-RADS ≤2)

Primary outcome

Cumulative incidence of clinically significant prostate cancer (Gleason ≥3+4)

Effect

7-year incidence 5.5% (PSAD <0.10) vs 13.8% (0.10–0.15) vs 11.9% (≥0.15); P < 0.001

What to do after a negative prostate MRI (PI-RADS 2 or less) is one of the commonest unanswered questions in prostate cancer diagnosis. This pre-specified analysis of the Swedish population-based Göteborg-2 screening trial followed 1685 men with a negative initial MRI for a median 5.5 years.

Eighty clinically significant cancers (Gleason 3+4 or higher) were found, 22 of them Gleason 4+3 or higher. At seven years, cumulative incidence was 7.1% overall: 5.5% with PSA density below 0.10 ng/mL², 13.8% at 0.10 to 0.15 and 11.9% at 0.15 or above. Most repeat MRIs (87%) stayed negative. But the lowest-density group still produced 42 significant cancers, including 12 Gleason 4+3 or higher. Modelling a strategy of PSA every two years with repeat MRI only when density reached 0.10 would cut MRI use by 60% and biopsies by 46%, and halve detection of insignificant cancer — while delaying 17% of significant diagnoses.

For practice, PSA density turns a negative MRI into a stratified plan: closer follow-up at 0.10 or above, lighter follow-up below it — but not discharge. Where MRI capacity is scarce, as in most of India, a density-guided approach concentrates scans where they find cancer.

• Calculate PSA density (PSA ÷ MRI prostate volume) for every man with a negative prostate MRI.
• At density 0.10 ng/mL² or above, plan closer follow-up with repeat PSA and a low threshold for repeat MRI.
• Below 0.10, continue PSA surveillance every one to two years rather than discharging.
• Repeat MRI or biopsy if PSA or density rises during follow-up.
• Explain to men that a negative MRI lowers but does not remove the risk of significant cancer.

Why it matters

It gives a simple, available number for deciding who needs another MRI, conserving scarce scanner time.

Don't overread it

The follow-up strategy was modelled, not tested, and it would delay some significant diagnoses; a low density is not a reason to discharge. Men came from a population screening trial; apply cautiously to men referred with symptoms.

The statistics, in plain English

Cumulative incidence of 5.5% vs 13.8% means about one man in 18 versus one in 7 was diagnosed with significant cancer within seven years. Even in the lowest group, significant cancers occurred, which is why surveillance continues.

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