Eur Urol Oncol: Prediction of biochemical recurrence after radical prostatectomy based on T stage based on magnetic resonance imaging

Currently, the local stage of prostate cancer (PCa) still relies on digital rectal examination (DRE).

Therefore, DRE remains the standard for
risk stratification in guideline recommendations, clinical trials, and patient consultations.
Over the past 20 years, multiparametric magnetic resonance imaging (mpMRI) has become the most influential diagnostic tool in the PCa Bureau, so the issue is becoming increasingly controversial
.

Recently, researchers from Spain published an article in Eur Urol Oncol comparing various T staging models based on DRE or mpMRI for predicting early biochemical recurrence (BCR) after radical prostatectomy (RP).

The researchers conducted a retrospective multicenter cohort study
between 2014 and 2021.
A total of 1,436 patients
were enrolled in eight referral centres in France, Italy, Switzerland and Belgium.
BCR is defined as a prostate-specific antigen value of ≥0.
2 ng/mL
during two follow-up visits.
Harrell's Consistency Index (C-index) was used to compare DRE-based (Model 1: CT1 vs cT2 vs cT3) or mpMRI (Model 2: Organ-Localized Disease vs Extracapsular Dilation [iECE] vs Seminal Vesicle Invasion [iSVI]; Model 3: Prostate Imaging-Reporting and Data System [PI-RADS]≤3 vs PI-RADS 4 vs PI-RADS 5; Model 4: iT2a [PI-RADS ≤3] vs iT2b [PI-RADS 4] vs iT2c [PI-RADS 5 excluding ECE or SVI] vs iT3a [ECE] vs iT3b [SVI]) 4 models in predicting BCR
performance.

Overall, 74 (5%), 845 (59%), 482 (34%) and 35 (2%) patients had low, intermediate, high, and very high risk PCa
, according to the Mazzone risk classification.
After a median follow-up of 16 months, 113 patients experienced BCR
.
Although the new mpMRI-based 5-group T staging system (Model 4) has the highest prognostic ability in multivariate analysis to predict early BCR (C index of 0.
694), there is overlap
between the 95% confidence intervals of the model.
In sensitivity analysis, when excluding cN1 patients and comparing with 5 groups of T classification based on DRE (cT1c vs cT2a vs cT2b vs cT2c vs cT3), the new mpMRI-based T staging model still had a higher C index in predicting BCR than DRE, but the 95% confidence intervals for each model still overlapped
.
The main limitation of the studies was the short
follow-up period.

The performance of four T-staging models in predicting post-RP BCR

In summary, the researchers elaborated an alternative mpMRI-based T stage that can be used to predict early BCR
after PCa RP.
However, the results need to be externally validated before they can be applied to clinical practice
.

Original source:

Michael Baboudjian， Bastien Gondran-Tellier， Alae Touzani et al.
Magnetic Resonance Imaging-based T-staging to Predict Biochemical Recurrence after Radical Prostatectomy： A Step Towards the iTNM Classification.
Eur Urol Oncol.
Oct 2022