Elsevier

Human Pathology

Volume 32, Issue 1, January 2001, Pages 74-80
Human Pathology

Original Contributions
Interobserver reproducibility of Gleason grading of prostatic carcinoma: Urologic pathologists

https://doi.org/10.1053/hupa.2001.21134Get rights and content

Abstract

Gleason grading is now the most widely used grading system for prostatic carcinoma in the United States. However, there are only a few studies of the interobserver reproducibility of this system, and no extensive study of interobserver reproducibility among a large number of experienced urologic pathologists exists. Forty-six needle biopsies containing prostatic carcinoma were assigned Gleason scores by 10 urologic pathologists. The overall weighted kappa coefficient κw for Gleason score for each of the urologic pathologists compared with each of the remaining urologic pathologists ranged from 0.56 to 0.70, all but one being at least 0.60 (substantial agreement). The overall kappa coefficient κ for each pathologist compared with the others for Gleason score groups 2-4, 5-6, 7, and 8-10 ranged from 0.47 to 0.64 (moderate-substantial agreement), only one less than 0.50. At least 70% of the urologic pathologists agreed on the Gleason grade group (2-4, 5-6, 7, 8-10) in 38 (“consensus” cases) of the 46 cases. The 8 “nonconsensus” cases included low-grade tumors, tumors with small cribriform proliferations, and tumors whose histology was on the border between Gleason patterns. Interobserver reproducibility of Gleason grading among urologic pathologists is in an acceptable range. HUM PATHOL 32:74-80. Copyright © 2001 by W.B. Saunders Company

Section snippets

Materials and methods

Two of the authors (W.C.A. and J.I.E.) collected, from several sources, 46 hematoxylin and eosin-stained glass slides of prostatic needle biopsies containing prostatic carcinoma. The amount of tumor on each slide ranged from microscopic foci to extensive. Examples of the spectrum of Gleason scores were included. No effort was made to make the cases particularly difficult.

The slides were distributed for Gleason grading to 9 additional urologic pathologists (M.B.A., D.G.B., P.A.H., E.C.J.,

Results

The overall κw for interobserver agreement for exact scores 2-10 for each of the urologic pathologists, used as the reference standard for each of the others (Table 1, pathologists not in alphabetical order), ranged from 0.56 to 0.70, with only one κw (0.56) less than 0.60 (substantial agreement).

. Weighted Kappa, All Possible Pair Combinations of Urologic Pathologists, 46 Cases, Gleason Scores 2-10

Empty CellReference Pathologist
Comparison Pathologist12345678910
1.63.52.70.59.58.74.66.69.84
2.63.59.78.74.70

Discussion

There is some variability in interobserver agreement among urologic pathologists, but the overall κw for scores 2-10 are, with one exception (0.56), greater than 0.60 (substantial agreement). This is better agreement than most other studies in which κw was calculated. Some studies had similar or better exact or ±1 agreement, but these had only a pair of participating pathologists or a prestudy primer or agreement on criteria (reviewed in ref 2). Further, the overall interobserver agreement is

Acknowledgements

The authors thank Michelle Page and JoAnn Higdon for secretarial assistance, Laura McKie for preparing the Tables, and Cheryl Nichols for photographic assistance.

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