Role of Inter-Observer Variability and Quantification of Muscularis Propria in the Pathological Staging of Bladder Cancer

Abstract Introduction Pathological staging of bladder cancer (BC) on trans-urethral bladder resection (TURB) specimens is critical for the indication of radical cystectomy (RC). Materials and Methods We aimed to assess the inter-observer variability among dedicated and not dedicated genito-urinary pathologists (GUP) and the predictive value of the amount of muscularis propria (MP) in the TURB specimens to predict accurate staging in RC. We selected 101 patients with at least 1 diagnosis of pT1 high grade BC who underwent RC during the history of disease. All the pathological TURB and RC specimens were reviewed by 3 GUPs, and concordance among them and with the original pathology report (OPR) was made. The presence and the extent of MP was measured in all the TURB specimens and correlated to stage at RC. Results Excellent (0.90 ≥ K ≥ 0.74) diagnostic concordance was reached among GUP while only good (0.77 ≥ K ≥ 0.67) with the OPR on stage and grade in TURBs. We found a general up-stage in the OPR compared with the GUP review. After histological review, 34.4% cases were downstaged to pT1 from pT2 and 10.1% from pT1 to pTa. The presence of MP was associated with a better discrimination of the stage at RC ( P  = .00065), and a trend towards correlation was found with its extent (area under the curve-receiver operator characteristic = 0.752; best cut-off 3.69 mm). Conclusion The implementation of dedicated GUP can improve diagnostic sensitivity and specificity in BC diagnosis. The amount of MP and perhaps its extent in pT1 TURB speciments can predict more accurate cancer stage at RC.