Could imaging be used for routine screening for prostate cancer in healthy men — similar to mammography for breast cancer screening?
A quick scan — with 15-minute, contrast-free MRI — detected more clinically significant prostate tumors than the usual screening with a blood test for prostate specific antigen (PSA) in a study of 408 British men.
The quick MRI scan detected 14 Gleason 3+4 or higher cancers while PSA screening detected 7 such tumors.
The trialists note that the study was not powered to evaluate differences in detection rates of clinically significant cancers, and so a larger or randomized trial is needed “to definitively prove these differences.”
Even so, the findings raise the possibility of using imaging for routine prostate cancer screening, they comment.
The goal is to find something better than routine PSA testing, which is notorious for sometimes missing dangerous tumors (underdiganosis) while picking up ones that would never cause men problems if left alone (overdiagnosis).
“This study suggests that when screening the general population for prostate cancer, MRI…may provide a better balance between the potential benefits and harms of screening” than PSA, say the researchers led by David Eldred-Evans, MBBS, of the Department of Surgery and Cancer at Imperial College London, United Kingdom.
Results from this trial, dubbed the IP1- PROSTAGRAM study, were published online February 11 in JAMA Oncology.
The study is the first to compare MRI, as well as transrectal ultrasound, and PSA screening directly. The results showed that ultrasound was similar to PSA in detecting clinically significant tumors, but quick MRI appeared better.
The findings “clearly point to prostate MRI as a promising screening test,” comment radiologists Susanna Lee, MD, PhD, and Aileen O’Shea, MBBCh, both of Massachusetts General Hospital, Boston, in an accompanying editorial.
“Future trials should be designed to include MRI in the prostate cancer screening strategy with image acquisition and interpretation protocols that are widely accessible, well tolerated, and readily generalizable,” they add.
“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,” they comment.
The study sought participants (men aged 50-69 years) from flyers, radio ads, and other community outreach recruitment efforts.
The response rate to the recruitment efforts was about 20%. To overcome historical underrepresentation in prostate cancer studies, the team targeted racial/ethnic minorities; the final cohort was 38% White, 32.4% Black, 23% Asian, and 6.6% other or mixed-race.
All participants underwent all three screening procedures (MRI, ultrasound, and PSA blood test), often on the same day,.
If any one screening tests was positive, that individual would undergo a systematic 12-core biopsy, with additional biopsies of sites with imaging abnormalities.
A PSA at or above 3 ng/mL was considered positive, as was an MRI score of 3-5 based on version 2 of the Prostate Imaging-Reporting and Data System (PI-RADS). A positive on transrectal ultrasound was a shear wave elastography score of 3-5 points based in part on World Federation for Ultrasound in Medicine and Biology guidelines (with a score of 3 for possible malignancy and 5 for highly likely malignancy).
Overall, 167 men ended up having a biopsy with 17 clinically significant and 20 clinically insignificant cancers detected.
Forty men (9.9%) were positive by PSA, leading to the detection of six clinically insignificant cancers along with the seven significant tumors.
Seventy-two men (17.7%) were positive by an MRI score of 3-5; eight of the 14 clinically significant tumors were in men with normal PSAs. Seven clinically insignificant tumors were also detected, six of them in men who were negative on PSA.
Forty-three men (10.6%) were positive by MRI when scores were limited to 4-5 points, including 11 worrisome cancers — five of which were negative by PSA — and five clinically insignificant tumors, four of them PSA negative.
The results suggest that an “MRI using a score of 4 or 5 to define a positive test result, compared with PSA testing alone at a level of 3 ng/mL or higher, might lead to more men being diagnosed with clinically significant cancer, without increasing the number of men advised to undergo biopsy or overdiagnosed with clinically insignificant cancer,” the investigators concluded.
It’s unknown at this point if downstream cost savings from more accurate testing would offset the extra upfront costs of MRI screening.
Also, radiologists agreed on fewer than 71% of their MRI interpretations, probably because MRI prostate cancer screening has not been standardized in the general population.
“If MRI is to be developed for use as a screening tool, additional efforts will need to be directed toward standardizing the imaging procedures for more reproducible results,” the editorialists commented.
As for ultrasound, 96 men (23.7%) were positive by a score of 3-5, which detected nine clinically significant and 13 insignificant tumors. Fifty-two (12.8%) were positive by an ultrasound score of 4-5, which detected four significant and seven insignificant cancers. “There was no evidence that ultrasonography would have better performance compared with PSA testing alone,” the investigators said.
The work was funded by the Wellcome Trust and others. Eldred-Evans reported equipment support from SuperSconic, and another investigator reported grants and/or personal fees from Sophiris Biocorp, Sonacare, Boston Scientific, and Trod Medical. The editorialists have disclosed no relevant financial relationships.
JAMA Oncol. Published online February 11, 2021. Full text, Editorial
M. Alexander Otto is a physician assistant with a master’s degree in medical science and a Newhouse journalism degree from Syracuse University. He is an award-winning medical journalist who worked for McClatchy and Bloomberg before joining Medscape, and also a MIT Knight Science Journalism fellow. Email: [email protected]
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