Table 1: AUA Risk Stratification for NMIBC
Furthermore, the presence of variant histology, lymphovascular invasion (LVI), and prostatic urethral involvement are considered especially high-risk features. Risk stratification is prognostic and is the primary driver of determining treatment, with patients with low-risk NMIBC recommended surveillance following transurethral resection of bladder tumor (TURBT) whereas patients with intermediate and high-risk disease are recommended induction intravesical therapy. Furthermore, patients with very high-risk features may be considered for early cystectomy. Pathologic interpretation of TURBT specimens drives NMIBC risk stratification, yet there is limited data on interobserver variability in TURBT pathology signout.
In this study, we sought to determine the frequency with which pathologic rereview of TURBT specimens by specialized genitourinary (GU) pathologists leads to changes in AUA risk stratification of NMIBC. We identified all patients with NMIBC who underwent TURBT at an outside institution and had TURBT pathology rereviewed by GU pathologists at Cleveland Clinic in 2021 and 2022. All patients included in this study had pathology rereview requested by the managing Urologic Oncologist at our institution. Cases in which pathology re-review was requested by an outside physician or because of diagnostic uncertainty were excluded. Cases in which pathology re-review led to a change in risk stratification were identified.
A total of 113 patients with NMIBC who met inclusion criteria were identified. Pathology rereview led to upgrading in 12 patients (11%), downgrading in eight (7%), and no change in 93 (82%). Upstaging occurred in six patients (5%), downstaging in six (5%), and no change in 101 (90%). Pathology rereview resulted in a change in risk stratification in 24 patients (21%), with 15 patients (13%) recategorized into a higher risk group and nine (8%) recategorized into a lower risk group. Changes in grade and stage were the most common factors leading to a change in risk stratification. Among patients with a change in risk stratification based on TURBT pathology rereview, these results likely impacted patient management, although this was not directly evaluated in this study.
Although this study was not designed to examine the causes of discordance between initial and GU subspecialty pathology review, we did observe that all cases in which risk stratification changed were initially reviewed by a pathologic without fellowship training. This observation is purely hypothesis-generating, however further study is needed to determine the impact of training and clinical volume on the accuracy of pathology signout and to identify other causes of interobserver variability.
Our observations highlight the importance of accurate TURBT pathologic interpretation in risk stratification and guiding patient management. The high incidence of changes in NMIBC risk stratification suggests that subspecialty GU pathology review of TURBT should be considered. Further study is needed to identify and address causes of interobserver variability in pathology signout.
Figure 1 – Sankey Diagram Demonstrating the Observed Changes in NMIBC Risk Stratification Following Pathology Rereview for 24 of 113 Patients (21%) in Whom Risk Stratification Changed Following Pathology Rereview.
Written by: Nima Almassi, MD, Urologist, Center for Urologic Oncology, Cleveland Clinic, Cleveland, OH
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