U.K. study suggests MRI is the most effective option

Magnetic Resonance Imaging (MRI) appears to be the best prostate cancer screening option, according to researchers in the United Kingdom.

A prospective, population-based study showed that when screening the general population for prostate cancer, MRI using a score of 4 or 5 (on a 5-point scale) to define a positive test result, compared with PSA testing alone at a level of 3 ng/mL or higher, leads to more men being diagnosed with clinically significant cancer.

In addition, researchers led by David Eldred-Evans, MBBS, determined that those men with significant cancers could be diagnosed with MRI without increasing the number of men who were advised to undergo biopsy or were diagnosed with clinically insignificant cancer.

Their study was published in JAMA Oncology.

Population screening programs for prostate cancer are not currently recommended by the United States Preventive Services Task Force or U.K. National Screening Committee. In place of universal screening, men are advised to make individual decisions about whether to be screened after a conversation with their clinician about the potential benefits and harms of screening.

In a commentary accompanying the study, Susanna I. Lee, MD, PhD, and Aileen O’Shea, MBBCh BAO, both of the Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, wrote that these findings “clearly point to prostate MRI as a promising screening test.”

Future trials should include MRI image acquisition and interpretation protocols that “are widely accessible, well tolerated, and readily generalizable,” they suggested. “In the long run, if successful, prostate MRI will be able to join mammography and low-dose computed tomography of the thorax as an imaging screening test that saves lives and improves the general health of the population.”

According to a 16-year follow-up European Randomized study of Screening for Prostate Cancer, when repeated at 2- to 4-year intervals PSA testing can reduce the mortality risk associated with prostate cancer by approximately 20%. However, PSA testing can also underdiagnose clinically significant cancers and overdiagnose clinically insignificant cancers that do not need treatment.

Multiparametric, contrast-enhanced MRI has been shown to be quite accurate in detecting clinically significant cancer in men with elevated PSA levels. In this study Eldred-Evans and his colleagues wanted to compare biparametric, noncontrast (short) MRI, as well as transrectal ultrasonography, with PSA testing as screening tools for prostate cancer.

The prospective, population-based, blinded cohort study included 408 men who underwent screening with a PSA test, MRI (T2 weighted and diffusion), and ultrasonography (B-mode and shear wave elastography). These men were 50 to 69 years of age with a life expectancy of at least 10 years, had not undergone PSA testing or prostate MRI in the previous 2 years, nor had a urinary infection or prostatitis in the previous 6 months, or history of prostate biopsy, prostate cancer, or any contraindication to MRI.

The imaging tests were reported on a validated 5-point scale of suspicion, with positive results defined as scores of 3-5, and 4-5.

Eldred-Evans and his colleagues found that 17% of the men had a positive MRI score of 3-5, 23.7% had a positive ultrasonography results of 3-5, and 9.9% had a positive PSA result. When a positive imaging results were defined as scores 4-5, 10.6% of men had positive MRI results and 12.8% had positive ultrasonography results – both of which were similar to the PSA results.

Thirty-seven prostate cancers were identified on combined targeted and systematic biopsy, 17 of which were clinically significant and 20 clinically insignificant.

Of the clinically significant cancers the PSA test (3 ng/mL) detected 7 cancers, an MRI score of 3 to 5 detected 14, an MRI score of 4 to 5 detected 11, an ultrasonography score of 3 to 5 detected 9, and an ultrasonography score of 4 to 5 detected 4.

Of the clinically insignificant cancers PSA testing diagnosed 6 cancers, an MRI score of 3 to 5 diagnosed 7, an MRI score of 4 to 5 diagnosed 5, an ultrasonography score of 3 to 5 diagnosed 13, and an ultrasonography score of 4 to 5 diagnosed 7.

“Population-based screening tests should have a well-defined and agreed-on cutoff point that is set to maximize detection of potentially life-threatening cancers while minimizing harms from false-positive results and overdiagnosis,” wrote Eldred-Evans and his colleagues. They added that their findings suggest that an MRI score of 4 or 5 may provide a better balance between the potential benefits and harms of screening, while ultrasound at either score threshold would not improve upon PSA testing in terms of the trade-off between benefits and harms.

  1. The use of MRI to screen for prostate cancer appears to be more successful in detecting clinically signficant cancers.

  2. Using MRI screening did not result in an increase in the number of men who were advised to undergo biopsy.

Michael Bassett, Contributing Writer, BreakingMED™

Eldred-Evans reported receiving grants from the BMA Foundation for Medical Research, The Urology Foundation, and the Royal College of Surgeons of England during the conduct of the study; grants from Imperial Health Charity outside the submitted work; and equipment support from SuperSonic Inc.

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