Tag: prostate screening

MRI Makes Prostate Screening More Precise

Posted on by Brian Casey

Prostate cancer screening isn’t a guideline-directed screening test yet, but this could change with the use of MRI and other tools. A series of papers published in several JAMA journals late last week indicates the progress that’s being made. 

As we’ve discussed in previous issues, prostate screening with PSA tests hasn’t met the threshold for clinical benefit achieved by other population-based screening exams.

  • PSA-based screening has been characterized by lower mortality benefits and relatively high rates of overdiagnosis and complications from follow-up procedures. 

But some researchers believe that PSA screening could be made more effective by using additional diagnostic tools like imaging and blood tests to focus on potentially high-risk disease for biopsy while active surveillance is used for less threatening prostate lesions. 

In the ProScreen trial in Finland, researchers tested the combination of PSA, a kallikrein four-panel blood test, and MRI in selecting patients for biopsy. 

  • Patients were sent to MRI if they had PSA scores of 3.0 ng/mL or higher and kallikrein scores of 7.5% or higher; those with abnormal MRI scans got targeted biopsy. 

The researchers tested the ProScreen protocol in a study of 61.2k men, with 15.3k invited to screening and 7.7k getting screened. Over a preliminary three-year follow-up period, researchers found …

  • 9.7% of men met the PSA threshold for a suspicious lesion; this fell to 6.8% after the kallikrein test and 2.7% after MRI, illustrating the protocol’s ability to reduce biopsies
  • Biopsy yield for high-grade cancer was 1.7%, which an editorial called a “remarkably high yield”
  • Overdetection of low-grade disease was 0.4%, compared to 3.2% in a comparable previous study

In a second study, this one in JAMA Oncology, researchers performed a meta-analysis of 80.1k men from 12 studies in which MRI was used to direct patients to prostate biopsy after PSA testing, finding that MRI-directed protocols had …

  • Higher odds of detecting clinically significant prostate cancer (OR=4.15) compared to PSA screening alone
  • Lower odds ratio for biopsy (OR=0.28)
  • Lower odds ratio for detecting clinically insignificant cancer (OR=0.34)

Finally, a secondary analysis in JAMA of a large UK trial illustrates the challenges of prostate screening without MRI guidance. Researchers reviewed 15-year outcomes of the Cluster Randomized Trial of PSA Testing for Prostate Cancer (CAP), a study of 415k men,196k of whom were screened from 2002 to 2009 without the use of MRI, finding … 

  • PSA screening increased detection of low-grade cancer (2.2% vs. 1.6%) but not intermediate or high-grade disease
  • Screening reduced prostate cancer mortality by a small amount (0.69% vs. 0.78%)

The Takeaway

Taken together, new studies offer a roadmap toward making MRI an integral part of prostate screening, such that perhaps in years to come it can join other cancer tests as a population-based screening tool.

MRI’s Value for Prostate Screening

Posted on by Brian Casey

Among cancer screening tests, prostate screening could be the most problematic. But a new study published this week in JAMA Network Open offers guidance on the role that MRI can play in making prostate screening more effective – and opening the door to population-based screening.

The problem with prostate screening is that PSA tests often discover disease that’s either indolent or slow-growing. 

  • This can lead to a cascade of interventions that are expensive and have harms of their own. 

But prostate cancer remains a common – and deadly – cancer, with 1.5M cases globally in 2022, and it’s the second most commonly occurring cancer in men after lung cancer.

  • Given these statistics, there has to be a way to perform prostate screening more effectively.

MRI offers one such alternative, and a clinical consensus has emerged that performing a single MRI scan after a positive PSA result can help stratify men before biopsy. 

  • In this scenario, men might not be referred to biopsy if their MRI scan is negative, and adoption of this protocol has helped reduce prostate biopsies in PSA-positive men while still detecting clinically significant cancer.   

But if one MRI scan is good, are repeat MRI scans even better? In the new study, Swedish researchers investigated this question in a secondary analysis of the STHLM3-MRI trial, which involved repeat screening of 1.5k men 2-3 years after an original prostate screening.

Of the group who got repeat PSA and MRI screening, 667 men had PSA levels of 3 ng/mL or higher, the threshold for MRI testing, with the repeat scans finding … 

  • 51 men (7.6%) had equivocal lesions (PI-RADS score of 3)
  • 33 men (4.9%) had suspicious lesions (PI-RADS score of 4)
  • Only 10 men (1.5%) had lesions with PI-RADS scores of 4 or greater

The findings led the authors to conclude that cancer detection was “limited” in the second round of PSA and MRI prostate screening, and detection of low-grade tumors was low.

The Takeaway

At first blush, STHLM3-MRI may seem like a negative study, but it actually helps frame the debate over prostate cancer screening and MRI’s role by omitting the need for multiple repeat scans. The results also give clinicians confidence that it’s safe to omit prostate biopsies in men who have a single negative MRI result – a key finding in reducing the downstream costs of any population-based screening program.

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