1612 Interobserver Agreement in Pathologic Assessment of Pancreatic Ductal Adenocarcinoma Post-Neoadjuvant Chemotherapy: A Comparative Study of Scoring Systems and Stromal Changes

Document Type

Conference Proceeding

Publication Date

3-24-2025

Publication Title

Lab Invest

Keywords

aged, cancer inhibition, clinical article, comparative study, conference abstract, diagnosis, exocrine function, female, human, interrater reliability, Kaplan Meier method, male, neoadjuvant chemotherapy, pancreatic ductal carcinoma, reproducibility, scoring system, stroma, surgery, tumor regression, tumor volume, weakness

Abstract

Disclosures: Kerem Ozcan: None; Zhengfan Xu: None; Ejas Palathingal Bava: None; Qing Chang: None; Zongshan Lai: None; Brian Theisen: None; Beena Ahsan: None Background: The majority of pancreatic ductal adenocarcinoma (PDAC) are diagnosed at an advanced stage, and neoadjuvant chemotherapy (NACT) followed by surgery is the preferred treatment. Assessing the pathologic status of PDAC after NACT presents one of the most challenging tasks for pathologists due to issues including how to process specimens, evaluate and score tumor response, and achieve consistency and reproducibility. Design: Forty-five cases were included in our study. H&E slides were reviewed by 4 pathologists who were asked to evaluate the following parameters: tumor regression score (TRS) using College of American Pathologists (CAP) and Becker scoring systems as well as stromal changes such as fibrosis, exocrine atrophy and inflammatory response. All stromal changes were categorized as: none, mild, moderate and severe. All pathologists were blinded to original interpretation and interpretation of others. Relevant clinical and pathologic data were collected. Interobserver agreement and survival data were analyzed using Fleiss Kappa and Kaplan-Meier respectively. Results: In our cohort, F:M ratio was 20:25. The median age was 67 (range 55-75) and the median tumor size was 1.8 cm (range: 0-6 cm). Expert recommendations on complete/near-complete grossing of post-treatment cases were followed. There was substantial agreement between all four pathologists for CAP (κ = 0.76) and Becker scoring systems (κ = 0.70). Regarding the evaluation of stromal changes, there was substantial agreement for exocrine atrophy (κ = 0.76), fair agreement for fibrosis (κ = 0.21) and inflammation (κ = 0.24). When CAP regression scores 0, 1 and 2 were combined, they had significantly better prognosis compared to CAP score 3 (p = 0.02) (Figure 1). Stromal changes, like exocrine atrophy, fibrosis, and inflammatory response did not correlate with survival. For PDACs status post NACT, it is suggested that, 1 cm could be a better cut off between T1 and T2. When we analyzed our results, we noted that T1c had a prognosis similar to T1a and T1b, and was significantly better than T2 (Figure 2). [Formula presented] [Formula presented] Conclusions: NACT is increasingly utilized in PDAC treatment, therefore clear guidelines on grossing the tumor as well as better TRS systems need to be established. CAP-TRS system, while reproducible, does not aid in risk stratifying patients which may be a weakness. Due to being highly subjective, around 60% of the evaluated cases are reported as CAP Grade 2, making over-utilization of this category reducing its analytical significance

Volume

105

Issue

3

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