Use of serial mpMRI in AS cannot avoid the need for biopsies

An analysis of seven studies with 800 patients.

Can the Use of Serial Multiparametric Magnetic Resonance Imaging During Active Surveillance of Prostate Cancer Avoid the Need for Prostate Biopsies?—A Systematic Diagnostic Test Accuracy Review (2020, Review, Full Text)

"Abstract

Context
The role of multiparametric magnetic resonance imaging (mp-MRI) during active surveillance (AS) of prostate cancer needs evaluation. It remains unclear whether mp-MRI can replace prostate biopsies completely during AS.

Objective
To evaluate the diagnostic performance of mp-MRI for disease progression in men on AS for prostate cancer.

Evidence acquisition
This systematic review was performed in accordance with the Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). Cross‐sectional studies that evaluate the diagnostic performance of mp-MRI (index test) for disease progression compared with systematic and targeted prostate/template biopsies or a composite of this (reference standard) were included. A meta-analysis was performed using STATA with “metandi” and “midas” commands.

Evidence synthesis
Seven studies with 800 patients were included in this systematic review. The pooled pathological progression rate was 27%.The pooled sensitivity and specificity of mp-MRI for disease progression were 0.61 (95% confidence interval [CI]: 0.46–0.74) and 0.78 (95% CI: 0.54–0.91), respectively. Adjusting for a prevalence of disease progression of 30% results in a positive predictive value of 0.43 (95% CI: 0.39–0.46) and a negative predictive value of 0.81 (95% CI: 0.78–0.84). Significant heterogeneity was observed. The meta-regression analysis did not demonstrate any significant outliers.

Conclusions
It is not possible to supplant prostate biopsies with mp-MRI in AS protocols with the current level of evidence. There is significant institutional variation in the diagnostic performance of mp-MRI during AS. Institutions must internally audit the diagnostic performance of mp-MRI in the AS setting. AS protocols must be based on local diagnostic performance, rather than on international AS protocols that may have limited applicability at individual settings.

Patient summary
In this review, we explored the accuracy of multiparametric magnetic resonance imaging in diagnosing disease progression for patients who were enrolled in active surveillance programmes for prostate cancer."

From the Full Text:

"In this review, only studies in which patients had baseline mp-MRI, and systematic and targeted biopsies/saturation biopsies before enrolment in the AS programme were included, to ensure appropriate grade classification. Based on a pooled histological progression rate (27%) from the included studies in this review, a prevalence of 30% for disease progression was assumed. A deterministic model would suggest that in a population of 1000 men at risk of disease progression during AS of favourable-risk prostate cancer, where 300 men actually develop disease progression, mp-MRI will correctly identify 183 men as having disease progression but miss the remaining 117; for the 700 men who do not have disease progression, mp-MRI will correctly identify 546 as not having prostate cancer but will misclassify 154 men as having disease progression. The probabilistic models using likelihood ratios would suggest that mp-MRI does not meet the criteria of an accurate test for disease progression during AS (positive likelihood ratio: 2.74; negative likelihood ratio: 0.5)."

[Emphasis mine]

So my takeaway is we should think about this Mayo Clinic statement on AS that I just found by googling:...

"Collecting samples of cells from within your prostate is usually recommended one year after active surveillance begins. Biopsy may be repeated occasionally, as your doctor recommends, to determine how much the cancer has grown and to re-evaluate your Gleason score to see if the cancer remains slow growing."

...as reading, instead "Biopsy should be repeated as your protocol dictates"

When I asked my uro about his AS protocol (not for me, obviously), he said his is probably closets to JH's, which is one of the strictest. He said some of the others were pretty "loosey goosey." According to the above study, that isn't the type of AS protocol you want.

Djin

Thanks, Djin. This is valuable info. As a (distinct) non-scientist it's impossible for me to know with any certainty whether 800 patients represents a sufficient sample. But instinctively I would think it would, especially as it represents data from so many individual studies.

All the more reason for me to be glad I insisted on another biopsy following my MRI in May, which is finally scheduled for - drum roll please, maestro - Nov. 3rd.

David

Weird. I do see his post. Not sure what to tell you, other than try logging out then logging back in but I’m guessing you’ve done that.
Let me know if it happens in other threads. If it’s not just a one off I’ll ask re other forums if anyone is having the same issue

Djin - Are you reading posts on computer or tablet or phone? Have you tried another browser and/or cleared data from the browser?

I have had the issue with the last poster listed not showing at the end of the thread but usually can resolve it after a while. Sometimes it will happen on two browsers or devices which I can only blame on the forum so I share the odd behavior you have experienced. Hope you have not blocked him

So if I understand correctly it was the browser that was the issue?

Company I work for uses Chrome / GMAIL for corporate communications
We had quite a few issues yesterday but seems to be okay today

Very confusing. Sounds like the issue isnt with the forum software, for sure, though.