# Robot-Assisted Radical Prostatectomy: Concordance and Correlation Between Preoperative Positron Emission Tomography-Computed Tomography With Prostate-Specific Membrane Antigen (PET-CT PSMA) and Final Histopathological Report

## TL;DR

This study compares PET-CT PSMA scans with actual surgical results in prostate cancer patients, finding that while the scans are good at ruling out disease, they often miss or overestimate cancer spread.

## Contribution

The study provides new evidence on the diagnostic performance of PET-CT PSMA in predicting seminal vesicle and lymph node invasion in prostate cancer.

## Key findings

- PET-CT PSMA showed high specificity and NPV but low sensitivity for seminal vesicle and lymph node invasion.
- Correlation and agreement between PET-CT PSMA and histopathology were low for both seminal vesicle and lymph node invasion.
- Positive findings from PET-CT PSMA should be interpreted cautiously due to poor agreement with final histopathology.

## Abstract

Background: Positron emission tomography-computed tomography with prostate-specific membrane antigen (PET-CT PSMA) has revolutionized the preoperative staging of prostate cancer, particularly for assessing seminal vesicle and lymph node invasion. However, its correlation and agreement with definitive histopathology remain unclear.

Objective: The study aimed to evaluate the diagnostic performance, correlation, and agreement between PET-CT PSMA and final histopathological findings for seminal vesicle and lymph node invasion in patients undergoing robot-assisted radical prostatectomy.

Methods: This retrospective, single-center study included 194 patients who underwent PET-CT PSMA and radical prostatectomy. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy were calculated. Correlation (Spearman's rho) and agreement (kappa coefficient) between PET-CT PSMA and final histopathology were analyzed.

Results: Seminal vesicle invasion was detected in 11.9% of cases by histopathology and 12.4% by PET-CT PSMA, while lymph node invasion was reported in 4.8% and 10.3%, respectively. PET-CT PSMA exhibited high specificity (91.23% for seminal vesicles, 92% for lymph nodes) and high NPVs (91.76% and 96.84%, respectively), but low sensitivity (39.13% and 40%) and low PPV for lymph nodes (20%). Correlation between PET-CT PSMA and histopathology was low for seminal vesicle invasion (rho = 0.298; p = 0.0001) and lymph node invasion (rho = 0.232; p = 0.017). Agreement was also poor for seminal vesicle invasion (kappa = 0.298) and lymph node invasion (kappa = 0.217).

Conclusion: PET-CT PSMA demonstrates high specificity and NPV but low sensitivity, correlation, and agreement with final histopathology. While useful for ruling out disease, its positive findings should be interpreted with caution.