Interobserver variability between expert urologic pathologists for extraprostatic extension and surgical margin...

Area of Science:

• Uropathology
• Prostate Cancer Research
• Surgical Pathology

Background:

• Accurate pathologic staging, including Gleason score, pathologic stage, and surgical margin (SM) status, is crucial for post-radical prostatectomy management in prostate cancer.
• While Gleason score variability is documented, data on interobserver variability for pathologic stage and SM assessment are limited.

Purpose of the Study:

• To investigate interobserver variability among expert urologic pathologists in interpreting extraprostatic extension (EPE) and SM on radical prostatectomy specimens.
• To quantify agreement levels and identify factors contributing to discrepancies in EPE and SM assessment.

Main Methods:

• A panel of 3 urologic pathologists established a gold standard for 60 whole-slide images (WSIs) of radical prostatectomy specimens, categorized as positive, negative, or equivocal for EPE or SM.
• Twelve expert urologic pathologists independently reviewed these WSIs, blinded to the panel diagnoses, and provided diagnoses for EPE and SM.
• Statistical analysis, including specificity, sensitivity, accuracy, and kappa values, was used to assess interobserver agreement.

Main Results:

• High accuracy, specificity, and sensitivity were observed for both EPE and SM assessments when compared to the gold standard.
• Overall kappa values indicated good to excellent agreement for SM (0.74) and moderate agreement for EPE (0.63).
• Agreement was notably higher for definitive EPE and SM diagnoses compared to equivocal cases, particularly for EPE.

Conclusions:

• Urologic pathologists exhibit good to excellent interobserver agreement in evaluating EPE and SM in radical prostatectomy specimens.
• Interobserver variability is primarily associated with challenges in identifying a clearly definable prostatic capsule (for EPE) and the presence of crush/thermal artifacts (for SM).