Digital rectal exams for prostate cancer staging could become a thing of the past thanks to MRI. A new study in JAMA Network Open found that MRI performed as well as digital exams in determining the extent of prostate cancer disease.
Prostate cancer screening is moving closer to becoming a more widely accepted test, and MRI has played a major role in that evolution by enabling more precise workup of men with high PSA levels.
- But what about other aspects of prostate cancer diagnosis and treatment, such as staging men found to have clinically significant disease? It turns out MRI has a role to play there as well.
To learn more, researchers from Germany looked at data from 4.4k men with a median age of 66 and median PSA level of 7.4 ng/mL (anything over 3 ng/mL is typically referred for additional workup). All patients were scheduled for radical prostatectomy.
- Patients received digital rectal exams to assign clinical T stage and assess characteristics of cancer severity, such as local tumor extent, extracapsular extension, and seminal vesicle invasion.
This was compared to multiparametric MRI scans on 1.5T or 3T systems, with data reported using the PI-RADS scale. The study’s primary outcome was distant metastasis-free survival.
Among the patient cohort, researchers found…
- MRI staging was slightly more accurate than digital exams for predicting biochemical recurrence-free survival (C index = 0.62, with 0.5 representing chance-level prediction and 1 indicating perfect prediction).
- And MRI was also better at predicting distant metastasis-free survival (C index = 0.67).
- But MRI and digital exams were comparable when using four of the major prostate cancer risk classification systems in Europe.
What to make of the results? MRI didn’t have a huge advantage over digital rectal exams, but it was good enough for the authors to suggest that digital exams could be eliminated in favor of MRI workup instead.
- That would enable clinicians to avoid many of the digital exam’s shortcomings, such as subjectivity, operator dependency, and restricted ability to assess extracapsular extension or seminal vesicle invasion.
The Takeaway
This week’s study shows that MRI’s role in prostate cancer diagnosis and treatment goes beyond just screening, and the digital rectal exam’s role for patient staging could soon become a thing of the past in all but a few cases.
