MRI could replace DRE for prostate cancer staging

MRI-derived prostate cancer staging could be a suitable replacement for digital rectal exam (DRE) staging, according to research published July 15 in JAMA Network Open. 

A team led by Arthur Peyrottes, MD, from Saint-Louis Hospital in Paris, France found that MRI-based staging showed similar performance to traditional DRE-based staging for biochemical recurrence, distant metastasis, and overall survival. 

“These findings suggested that MRI-derived staging could be safely integrated into contemporary risk systems without compromising accuracy,” the Peyrottes team wrote. 

MRI has become more popular in prostate cancer staging by providing detailed anatomical information on local tumor extent. This allows for non-invasive assessment of extracapsular extension and seminal vesicle invasion. Traditional DRE meanwhile is limited as a screening tool, including for prostate-specific antigen (PSA) testing. 

Peyrottes and colleagues compared the performance of MRI-based and DRE-based clinical T staging in men undergoing radical prostatectomy. They also studied outcomes from substituting MRI staging in established prognostic classification systems. These included the following: D’Amico, the European Association of Urology, the National Comprehensive Cancer Network, and the International Staging Collaboration for Prostate Cancer. 

The study included 4,425 men with a median age of 66 years and median PSA level of 7.4. The researchers noted a median follow-up of 52 months. 

MRI-based staging showed slightly higher discriminatory ability than DRE staging for biochemical recurrence-free survival and metastasis-free survival. 

And across risk classification systems, both staging approaches showed comparable discrimination with overlapping 95% confidence intervals. 

The researchers also found no significant difference in time-dependent area under the receiver operating characteristic (AUROC) curves during follow-up between MRI and DRE staging. 

Finally, subgroup analyses showed comparable results between both approaches for patients with cT1 disease and those with PSA levels less than 10 ng/mL. 

The researchers noted that while MRI-based staging was more anatomically precise, it did not add information toward risk estimation already captured by PSA level, biopsy, and risk classification systems. 

“This reinforces the robustness of traditional risk systems, which remain valid and reliable in the modern MRI era,” they wrote. 

The study authors called for future prospective studies and incorporation of radiomic or genomic data. They wrote that these could “further clarify the oncologic risk estimation” value of MRI-based staging. 

The results support continued integration of MRI into modern diagnostic pathways while clarifying its role, according to an accompanying editorial written by Chadi Nabhan, MD, from Ryght AI in Anaheim, CA and Charles Bennett, MD, PhD, from the University of South Carolina in Columbia.

"MRI refines anatomy and informs clinical decision-making and potentially can improve quality of life through more informed treatment decisions but does not, in isolation, redefine risk," they wrote.

Read the full study here.