The Latest Advance in Prostate Cancer Screening: Micro-Ultrasound

One of the moments I find hardest in clinic is this: a 53-year-old man with no symptoms sits across from me. His PSA came back at 2.8 on a check-up. I have a blood value, a digital rectal examination finding and a grey image on conventional ultrasound that, frankly, tells me very little. And I need to give this man an answer as to whether "you definitely do not have prostate cancer at present".

For years we were never entirely comfortable answering that question, because a normal PSA did not mean a man was free of prostate cancer. And even with a digital rectal examination, we were missing prostate cancer in one man in five.

Over the past decade this picture has changed. First came prostate MRI, which has genuinely served us well. Now there is a technology that fills the gap MRI leaves: high-resolution micro-ultrasound.

I want to describe this technology on the occasion of Prostate Cancer Awareness Month. But let me say at the outset: the aim of this article is not to promote a new device. My aim is to explain where we have got to in prostate cancer and why a check-up appointment is more valuable than ever.

PSA Screening Is Useful, But Not Sufficient on Its Own

I think the PSA test has been treated unfairly. At one point the narrative that "PSA is unnecessary, it leads to overdiagnosis" or "PSA screening does not change death rates in men" became so widespread that screening rates fell and the number of patients we caught at an advanced stage rose. Yet ERSPC, Europe's largest screening study, showed after 16 years of follow-up that PSA screening reduced prostate cancer deaths by about 20%. That is not a figure to be dismissed.

The problem with PSA is not that it does not work; it is that it is not specific to cancer. PSA is a protein secreted by the prostate. It rises if the prostate is enlarged, it rises if there is inflammation, it rises if the man has cycled or had sexual intercourse before the test. Cancer also raises it - but that is only one of the possibilities. When PSA is the only piece of data we have, the only way to know whether cancer is present is to put a needle in.

There is another side to the coin: overdiagnosis. Some of the cancers we find are so slow-growing that the patient dies of something else entirely rather than of that cancer. Finding and treating such a cancer harms rather than helps the patient; both surgery and radiotherapy have a price.

Our goal is no longer to find more cancer: it is to find the cancer we need to find and to leave alone the cancer we should not find.

Prostate MRI Changed a Great Deal - But Not Everything

When multiparametric prostate MRI entered this picture we made a serious leap. We could see the suspicious area, direct the needle to it and spare some patients with a clear MRI from biopsy. Today all guidelines recommend MRI before biopsy, and that is the right recommendation.

But every urologist working in the field knows MRI's rough edges: appointments take time and the cost is high; it cannot be performed in patients with a pacemaker, severe claustrophobia or renal function unsuitable for contrast. Perhaps most importantly, the quality of an MRI depends largely on the experience of the radiologist reading it; the same images can become two different reports at two different centres. And there are cancers MRI simply does not see.

How Does Micro-Ultrasound Differ From Conventional Ultrasound?

The ultrasound machines we have used for decades in prostate examination operate between 6 and 12 MHz. With such a machine I can measure the volume of the prostate and look at its general structure, but I cannot see cancerous tissue directly. This is why a biopsy performed under conventional ultrasound guidance resembles a search without a map: samples are taken from 12 separate points in the prostate and the rest is left to chance.

Micro-ultrasound operates at 29 MHz. That means a resolution of about 70 microns - the size of the acini, the smallest structural units of the prostate. With micro-ultrasound the prostate is seen at tissue level. The disruption cancer creates in this micro-architecture - irregularity in the distribution of the acini, the typical "Swiss cheese" appearance, bright reflections - appears on the screen in real time.

It Can See Lesions Not Detected by MRI

Studies placing micro-ultrasound and MRI side by side consistently show one thing: the two methods do not see the same lesions. They overlap, but not completely.

• In one study, 206 of 244 lesions detected on MRI (84.4%) were also seen on micro-ultrasound. In the same study, micro-ultrasound revealed 26 additional lesions that MRI had not shown at all; targeted biopsies from these lesions caught 3 significant cancers that would otherwise have been missed.
• In a 682-man screening study published earlier this year, the concordance between micro-ultrasound and MRI findings was 69.2% - meaning that in one in three patients the two methods say different things.

This should be read not as a shortcoming but as an opportunity. The two methods work on different physical principles: MRI looks at the movement of water molecules in tissue and at vascularity, while micro-ultrasound looks at the mechanical structure and architecture of tissue. Naturally, one illuminates the other's blind spot.

Not Instead of MRI, But Alongside It

I want to be clear at this point, because the issue is often misunderstood: micro-ultrasound is not an alternative to MRI but a complement to it.

The OPTIMUM trial published in JAMA in 2025 showed that micro-ultrasound on its own does as good a job as MRI. This trial, which randomized 678 men at 19 centres in Canada, the United States and Europe, demonstrated that biopsy under micro-ultrasound guidance was not inferior to biopsy under MRI guidance. This is one of the highest levels of evidence an imaging method can attain and has moved micro-ultrasound out of the status of "a new device under trial".

It Should Be Routine in Screening - Because It Is Not Difficult

I will go one step further and say this as a clinician's opinion: micro-ultrasound should now be a routine part of prostate assessment. My reasoning is not complicated - this is not a difficult examination.

The average examination takes 3 minutes. The patient does not need a separate appointment, does not need to go to another floor, does not need to come back another day. The urologist performs it in the clinic as a continuation of the examination; sees the result immediately and discusses it with the patient in the same session. If necessary, the biopsy is performed in the same session, at the site seen. Compare this with the logistics of MRI: appointment, waiting, scan, writing the report, the patient returning for the report. The interval is often weeks, and the patient worries throughout.

The study published in Prostate Cancer and Prostatic Diseases in August examined exactly this scenario - men with no symptoms attending a routine check-up: 682 men, median age 59, median PSA only 1.2 ng/mL. Perhaps the most reassuring result of this study is this: when no suspicious area is seen in the prostate on micro-ultrasound, roughly nine out of ten men genuinely do not have a cancer requiring treatment. In other words, a "clean" image is not empty consolation but a real reassurance.

• The risk of overdiagnosis falls roughly sixfold.
• The risk of unnecessary biopsy falls roughly sevenfold.
• Compared with an MRI-based approach, no significant cancer was missed in the group micro-ultrasound found clear.

When Should You Come for a Check-Up?

For all this technological discussion to mean anything, you first have to come through the door. Prostate cancer gives no symptoms at an early stage; by the time symptoms appear it is usually late.

• From the age of 50, an annual urology check-up and PSA.
• If your father, brother or son has had prostate cancer, from the age of 45.
• If there is a family history of more than one prostate cancer or of breast/ovarian cancer (BRCA gene changes), from the age of 40.

Difficulty passing urine, a weakening urinary stream, getting up frequently at night, blood in the urine or semen, persistent back pain - if you have any of these, do not go by your age, see a urologist. The great majority of these complaints are caused by benign prostate enlargement; but we can only say so after examining you.

A Final Word

Let us return to the 53-year-old patient I described at the start. The answer I will give him today is very different from the one I would have given ten years ago. I no longer have only a PSA value: in screening I can see the prostate at tissue level with micro-ultrasound, I request multiparametric prostate MRI if a suspicious lesion is present, and I can compare the results of both methods. I make the biopsy decision by seeing, not by guessing.

Independently of the technology, the main thing I want to say is this: prostate cancer, when caught early, is in the great majority of cases a disease that can be brought under control. Devices will continue to advance; none of them replaces an appointment made in time.