Can multiparametric MRI replace Roach equations in staging prostate cancer before external beam radiation therapy?

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Accurate T-staging of prostate cancer (PCa) is crucial for treatment planning.
• Roach equations (RE) are a traditional method for estimating PCa T-stage.
• Multiparametric magnetic resonance imaging (mpMRI) offers detailed anatomical and functional information for cancer assessment.

Purpose of the Study:

• To compare the agreement between RE and mpMRI in assessing the T-stage of PCa.
• To evaluate changes in T-stage and risk category assignment based on mpMRI compared to RE.
• To determine the diagnostic performance of mpMRI for detecting locally advanced (≥T3) PCa.

Main Methods:

• Prospective mpMRI acquisition in 73 PCa patients before external beam radiation therapy (EBRT).
• Assessment of agreement using Cohen's kappa statistic for T-stage (≥T3 vs. T≤2) and risk category (National Comprehensive Cancer Network criteria).
• Validation of mpMRI's sensitivity and specificity for ≥T3 stage in 37 patients with post-prostatectomy histology.

Main Results:

• Moderate agreement observed between RE and mpMRI for T-stage (k=0.53) and risk category (k=0.56).
• mpMRI altered T-stage and risk category in approximately 21% of patients, predominantly downstaging PCa compared to RE.
• mpMRI demonstrated high sensitivity (81.8%) and specificity (88.5%) for detecting ≥T3 stage in the validation group.

Conclusions:

• RE and mpMRI exhibit only moderate agreement in PCa T-staging.
• mpMRI leads to a change in risk assessment for about one-fifth of patients, often downstaging the cancer.
• High sensitivity and specificity support mpMRI's utility as a preferred tool for pre-treatment PCa staging before EBRT.