Most (but not all) of the studies I've seen that looked at mpMRI, targeted biopsy, systematic biopsy, and targeted+systematic biopsy conclude that mpMRI with a targeted + systematic biopsy catches more clinically significant PCa (csPCa). I'm referring mainly to biopsy-naive men
who have some sign(s) that there may be PCa. Logically, too, that makes sense, although if mpMRI were exceptionally good, one would expect and hope that it, alone, could do the trick and biopsies could be reserved for only those men with suspicious mpMRIs (PIRADS 3-5).
I'm perplexed by the findings and conclusion of the following study which I saw this morning. I'll highlight what bothers me.
-----------------------------------------The "Is mpMRI Enough" or IMRIE Study: A Multicentre Evaluation of Prebiopsy Multiparametric Magnetic Resonance Imaging Compared with Biopsy
Background: Multiparametric magnetic resonance imaging (mpMRI) is now recommended prebiopsy in numerous healthcare regions based on the findings of high-quality studies from expert centres. Concern remains about reproducibility of mpMRI to rule out clinically significant prostate cancer (csPCa) in real-world settings.
[b/Objective: To assess the diagnostic performance of mpMRI for csPCa in a real-world setting
.Design, setting, and participants
: A multicentre, retrospective cohort study, including men referred with raised prostate-specific antigen (PSA) or an abnormal digital rectal examination who had undergone mpMRI followed by transrectal or transperineal biopsy, was conducted. Patients could be biopsy naïve or have had previous negative biopsies.Outcome measurements and statistical analysis
: The primary definition for csPCa was International Society of Urological Pathology (ISUP) grade group (GG) ≥2 (any Gleason ≥7)
; the accuracy for other definitions was also evaluated.Results and limitations
: Across ten sites, 2642 men were included (January 2011-November 2018).
Mean age and PSA were 65.3yr (standard deviation [SD] 7.8yr) and 7.5ng/ml (SD 3.3ng/ml), respectively. Of the patients, 35.9% had "negative MRI" (scores 1-2); 51.9% underwent transrectal biopsy and 48.1% had transperineal biopsy, with 43.4% diagnosed with csPCa overall. The sensitivity and negative predictive value (NPV) for ISUP GG≥2 were 87.3% and 87.5%, respectively. The NPVs were 87.4% and 88.1% for men undergoing transrectal and transperineal biopsy, respectively. Specificity and positive predictive value of MRI were 49.8% and 49.2%, respectively. The sensitivity and NPV increased to 96.6% and 90.6%, respectively, when a PSA density threshold of 0.15ng/ml/ml was used in MRI scores 1-2; these metrics increased to 97.5% and 91.2%, respectively, for PSA density 0.12ng/ml/ml. ISUP GG≥3 (Gleason ≥4+3) was found in 2.4% (15/617) of men with MRI scores 1-2
. They key limitations of this study are the heterogeneity and retrospective nature of the data.Conclusions
: Multiparametric MRI when used in real-world settings is able to rule out csPCa accurately, suggesting that about one-third of men might avoid an immediate biopsy
. Men should be counselled about the risk of missing some significant cancers.Patient summary
: Multiparametric magnetic resonance imaging (MRI) is a useful tool for ruling out prostate cancer, especially when combined with prostate-specific antigen density (PSAD).
Previous results published from specialist centres can be reproduced at smaller institutions. However, patients and their clinicians must be aware that an early diagnosis of clinically significant prostate cancer could be missed in nearly 10% of patients by relying on MRI and PSAD alone.
Note the authors do some hedging, saying mpMRI + PSAD is a "useful tool for ruling out prostate cancer" while at the same time saying "Multiparametric MRI when used in real-world settings is able to rule out csPCa accurately"So your doc comes in and tells you "Good news: your MRI didn't pick up anything suspicious of intermediate- or high-risk prostate cancer that warrants a biopsy. However, studies have shown that 10 in 100 men with this results actually do have prostate cancer that probably requires treatment. Also, 2 or 3 of those 10 men have high-risk cancer. If you are that guy, we're missing a chance to catch very serious PCa early. So what do you want to do?"
Of course I doubt a uro would base his mpMRI use on one study alone, and even if they did, they would give an opinion so that there could be joint decision-making
the biopsy. But, for argument's sake, taking this study as correct, I'm curious whether your agree with the author's "90% may be good enough" take on using mpMRI results to skip a biopsy
. (I vote no, but I had a G10 biopsy, so I probably have a clear bias for thinking this is too cavalier a stance).