Combining MRI-targeted, systematic biopsy best for prostate cancer diagnosis
medwireNews: A combined approach using both magnetic resonance imaging (MRI)-targeted and systematic biopsy provides improved diagnostic accuracy for the detection of prostate cancer versus either strategy alone, say the Trio researchers.
“[W]e found that combined biopsy leads to an increase in the number of cancer diagnoses and improves the likelihood that the biopsy findings are predictive of the true pathologic nature of the patient’s disease,” they write in The New England Journal of Medicine.
The team continues: “This knowledge should reduce the risks of both overtreatment and undertreatment out of fear of misdiagnosis.”
The Trio study – conducted by Peter Pinto and co-investigators from the National Cancer Institute in Bethesda, Maryland, USA, at their institution – included 2103 men with clinical suspicion of prostate cancer due to elevated serum prostate-specific antigen levels or an abnormal digital rectal exam. All participants underwent a multiparametric MRI-targeted biopsy followed by transrectal, ultrasonographically guided, 12-core systematic biopsy.
The rate of prostate cancer diagnosis was 51.5% with MRI-targeted biopsy alone and 52.5% with systematic biopsy alone, but was 62.4% with the combined approach.
Compared with systematic biopsy, MRI-targeted biopsy led to significantly more diagnoses of clinically significant disease, that is, cancers in grade groups 3, 4, and 5, and fewer diagnoses of cancer in grade group 1, which is considered to be clinically insignificant disease.
And of the 466 patients who were diagnosed with at least grade group 3 prostate cancer after combined biopsy, the majority (91.2%) were also detected by the MRI-targeted approach alone.
These findings “may argue for the use of MRI-targeted biopsy alone, since it is responsible for the detection of a majority of clinically significant cancers, requires 12 fewer biopsy cores, and leads to 5% fewer diagnoses of clinically insignificant cancers” than the combined approach, say the study authors.
But they also found that the use of MRI-targeted biopsy alone would have missed 123 cases of grade group 3 or higher cancers and 41 incidences of those classed as grade group 2 or higher in the study population.
Furthermore, among men who underwent radical prostatectomy, comparison of histopathologic specimens at biopsy and surgery showed that the likelihood of any upgrading or clinically significant upgrading was significantly higher with MRI-targeted biopsy alone than the combined approach, at rates of 30.9% versus 14.4% and 8.7% versus 3.5%, respectively.
This was also the case for systematic biopsy alone, for which the rates of any upgrading and clinically significant upgrading were 41.6% and 16.8%, respectively.
“Therefore, although combined biopsy resulted in a small net increase in the diagnosis of indolent cancers, its high predictive value for a patient’s true pathological grade group reduces the likelihood of misdiagnosis and should translate into decreased diagnostic uncertainty,” comment Pinto and colleagues.
They conclude: “Potentially, these data may usher in a new era of increased confidence in the selection of prostate cancer treatment on the basis of biopsy results.
“Future research may define pre-biopsy measures under which selected patients may undergo MRI-targeted biopsy only.”
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