The Chemotherapy Response Score (CRS): Interobserver Reproducibility in a Simple and Prognostically Relevant System for Reporting the Histologic Response to Neoadjuvant Chemotherapy in Tuboovarian High-grade Serous Carcinoma

Abstract

A 3-tier histopathologic scoring system, the chemotherapy response score (CRS), was previously devised for reporting the histologic response to neoadjuvant chemotherapy in interval debulking surgery specimens of stage IIIc/IV tuboovarian high-grade serous carcinoma. This has been shown to predict the outcome and offer additional information to other methods of assessing the treatment response. In the present study, the reproducibility of this scoring system was assessed by determining the interobserver agreement among reporting pathologists. A total of 5 groups each comprising 3 pathologists with different levels of expertise were selected. The participants underwent an online tutorial on how to apply the CRS system. 40 cases (38 cases in 2 appraiser groups) were scored individually by each of the 15 pathologists. The interobserver reproducibility was calculated using Fleiss' κ, Kendall's coefficient of concordance, and the absolute agreement between (a) individual pathologists within 1 group, (b) with the majority score agreement between all groups, and (c) with all individual scores. The CRS system was found to be highly reproducible among all the pathologists' groups (κ=0.761). The agreement in identifying the group of patients with the best response to chemotherapy was exceptionally high (κ=0.926). We conclude that CRS has a high interobserver reproducibility, especially in identifying the subgroup of patients with the best chemotherapy response, justifying its inclusion in clinical trials and reporting practice.

Chemotherapy Response Score in Ovarian Cancer Patients: An Overview of Its Clinical Utility

“…The development of the CRS aimed to provide an accurate scoring system that would permit an objective pathologist’s evaluation of the actual tumor response to chemotherapy. It is considered to be very precise, as the reported interobserver reproducibility seems to be exceptionally high, according to the findings of a previous study [ 15 ]. It is based on a 3-tiered system that evaluates the proportion of viable tumor cells and the presence of regression-associated fibroinflammatory changes.…”

Pathologic Classification of Ovarian Cancer

“…9). Morphologic evidence of the response to therapy is included in the pathology report in the form of the chemotherapy response score (CRS, Table 2) [19]. The CRS has been widely adopted, but it is important to recognize that it is based only on the amount of omental Fig.…”