Abstract

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• INTRODUCTION:

  Tumor grade plays a critical role in the management of papillary non-invasive urothelial carcinoma (UC). Since grading of UC relies on morphologic criteria, variability in interpretation exists among pathologists. The objective of this study was to examine inter-observer variability in the grading of papillary non-invasive UC at a single academic medical center.

  MATERIALS AND METHODS:

  One general pathologist and two genitourinary pathologists were blinded to patient identity and graded 98 consecutive UC specimens using the 1973 and 2004 classification systems. Kappa statistics (&b.kappa;) were used to measure inter-observer reproducibility to account for agreement expected purely by chance. By convention, &b.kappav; values from 0.21-0.4 represent 'fair', from 0.41-0.6 represent 'moderate', and > 0.6 represent 'substantial' agreement.

  RESULTS:

  Raw percentage agreement among all three pathologists was only 26% using the 1973 system and 47% using the 2004 system. When measured by kappa, overall agreement was only 'fair' for both systems and while higher for the 2004 system than the 1973, this was not significant (&b.kappav;: 0.38 versus 0.26, respectively). There were no significant differences in agreement when comparing the specialists agreement between themselves with agreement between each specialist and the generalist (&b.kappav;: 0.31-0.37 versus &b.kappav;: 0.18-0.46).

  CONCLUSIONS:

  The current grading system continues to demonstrate challenges in reproducibility among general and specialized pathologists. The degree of variability has significant implications on management decisions for non-invasive UC. Our findings underscore the need to identify molecular markers that can provide a more objective and reliable risk stratification system to guide patient management.