Should an MRI Come Before the Prostate Biopsy? Reading the PRECISION Trial

The short answer

PRECISION, a 500-man randomized trial published in the New England Journal of Medicine in 2018, tested whether doing an MRI before a prostate biopsy changes what gets found. The MRI-first pathway detected more clinically significant cancers, fewer insignificant ones, and let roughly a quarter of men skip biopsy altogether. That is a real result in the men who were studied. It describes what one trial measured, not a rule for any individual person.

What the old pathway looked like

For years the standard next step after a worrying PSA or an abnormal digital rectal exam was a transrectal ultrasound (TRUS) biopsy: a systematic sampling of the gland, usually 10 to 12 needle cores, guided by ultrasound that cannot actually see most tumors. The needles follow anatomy rather than a visible target. That approach has two well-documented failure modes. It can miss aggressive cancers hiding in undersampled zones, and it can stumble onto small, slow-growing tumors that were never going to cause harm, pulling men into treatment and its side effects for disease that did not need finding.

Multiparametric MRI offered a different starting point. If a scan could flag suspicious areas first, biopsy needles could be aimed at them, and men whose scans looked clean might avoid a biopsy entirely. PRECISION was designed to test that idea head to head.

What PRECISION actually did

The trial, led by Veeru Kasivisvanathan and colleagues and registered as NCT02380027, enrolled 500 men across 23 centers in 11 countries in Europe and North America. All of them had a clinical suspicion of prostate cancer, from an elevated PSA or an abnormal exam, and none had undergone a biopsy before. They were randomly assigned to one of two pathways.

In the standard group, men went straight to a TRUS biopsy. In the MRI group, men had a multiparametric MRI first. If the scan showed a suspicious area, they had a targeted biopsy of that area only, with no systematic sampling. If the scan showed nothing suspicious, they had no biopsy at all and were followed.

The primary outcome was the proportion of men found to have clinically significant cancer, defined in the trial as a Gleason score of 3+4 (a score of 7) or higher. That definition matters, because the whole question is not whether MRI finds more cancer of any kind, but whether it finds more of the cancer that actually warrants attention.

What the trial found

More men in the MRI group were diagnosed with clinically significant cancer: 38 percent, compared with 26 percent in the standard-biopsy group. After adjustment, that was a difference of about 12 percentage points favoring the MRI pathway, and the result was statistically significant.

At the same time, the MRI pathway diagnosed fewer clinically insignificant cancers, the low-grade tumors most likely to represent overdiagnosis: 9 percent versus 22 percent with standard biopsy. In other words, the MRI-directed route shifted the yield toward the cancers that matter and away from the ones that mostly generate anxiety and intervention.

The third finding is the one patients often feel most directly. Of the men randomized to the MRI pathway, 71 of 252, roughly 28 percent, had scans that were not suggestive of cancer and therefore did not undergo a biopsy at all. A biopsy is not a trivial event; it carries a risk of infection, bleeding, and discomfort. Sparing more than a quarter of men that procedure, while still catching more significant disease, is the combination that made this trial influential.

Reading it honestly

A single trial, however clean its design, is a measurement made under specific conditions, and the conditions here deserve attention. PRECISION studied men with no prior biopsy, so its results do not automatically transfer to men being re-evaluated after an earlier negative biopsy or to men already under active surveillance. The MRI arm depended on high-quality scans read by experienced radiologists at academic centers; MRI quality and reader skill vary in the real world, and a pathway that lets a negative scan cancel a biopsy is only as safe as the scan behind it.

There is also a genuine trade-off buried in that 28 percent who skipped biopsy. Forgoing biopsy after a reassuring MRI means accepting a small chance that a significant cancer was present but not seen. PRECISION was not designed or sized to measure long-term outcomes such as metastasis or survival; it measured what was detected at diagnosis. Later work, including guideline reviews and follow-on analyses, has examined how many significant cancers an MRI-first strategy might miss, and the honest answer is that the number is low but not zero. That is why guideline bodies such as NICE, in England, moved to recommend multiparametric MRI before biopsy for men with suspected localized prostate cancer while still building in systematic safeguards.

None of this tells any particular reader what to do. Whether an MRI belongs before a biopsy in a given situation depends on the reason for suspicion, the local imaging quality, prior test history, and a person's own weighing of the risks of missing disease against the risks of an unnecessary procedure. This article is educational and is not medical advice; those decisions belong to a person and their own clinician.

What PRECISION did establish is narrower and still important. In previously unbiopsied men, putting a good MRI at the front of the pathway changed the mix of what got diagnosed, toward significant cancer and away from insignificant cancer, and it let many men avoid a biopsy without an obvious cost in detection. That is a trade-off worth understanding, not a verdict to be applied by formula.