MRI overutilized in prostate cancer screening, study finds
It may be time to rethink clinical guidelines for prostate cancer screening after new research shows MRI scans often do not reveal lesions indicative of cancer, even in men with high levels of prostate-specific antigen (PSA). The full study findings are published in the journal Urology. [1]
In repeated prostate cancer screenings, the detection of clinically significant cancer was limited, especially low-grades of cancer, despite markers indicative of the illness. This left researchers from Sweden led by Tobias Nordström, MD, PHD from the Karolinska Institute to question if MR imaging is useful in the detection of early stages of prostate cancer, or if imaging resources are being wasted.
In a secondary analysis of a previous randomized clinical trial involving the use of MR imaging to diagnose prostate cancer, researchers investigated the outcomes of repeated screenings using PSA testing, followed by an MRI scan. Review of records of 1500 men (aged 50 to 74) who had follow-up testing 2 to 3 years after their initial screening showed that 667 of the men (44.5%) had PSA levels of 3 ng/mL or greater—a sign of elevated prostate cancer risk. Of that group, 617 (92.5%) underwent a second MRI, but only 51 were found to have lesions (7.6%), and an additional 33 (4.9%) had suspicious findings that warranted further evaluation.
“Early detection of prostate cancer using PSA testing and MRI has previously been shown to maintain detection of clinically significant disease and to decrease the high rates of overdiagnosis associated with traditional workup. However, because no benefit for prostate cancer–specific mortality has been observed from a single PSA test, the performance of prostate cancer detection in the repeat testing setting is crucial,” Nordström and the co-authors wrote. “In this study, compliance with repeat prostate cancer screening was reasonably high, and a substantial proportion of men who had repeat screening were reclassified as having elevated risk and thus offered workup. In line with this finding, the number of MRI scans in repeat screening was high, whereas the proportion of MRI scans that indicated suspicion of prostate cancer was low.”
Of the 1500 men who received follow-up prostate screenings, only 48 (3.2%) were diagnosed with cancer. To the researchers, this calls into question clinical protocols, especially since secondary MRI scans were used on a large number of the cohort due to their high chance of having prostate cancer. Based on PSA levels, the presumed rate of positive diagnoses was expected to be higher.
“The high proportion of negative MRI results is striking, and it would lead to an overutilization of MRI resources if used for biannual prostate cancer screening in combination with PSA levels of 3 ng/mL or greater as the cutoff for a single-biomarker strategy for further workup. This supports the use of reflex testing in men with moderately elevated PSA levels in a screening program,” the authors added.
The authors note that the findings underscore the challenges and limitations associated with repeated screening for prostate cancer using PSA testing as a measure for the necessity of an MRI. Future research should focus on developing strategies to enhance the efficiency of MRI-based screening protocols while minimizing unnecessary use, they said, so vital imaging time is not wasted on patients who are unlikely to benefit.
The full study is available at the link below.
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