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.
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.