Regression grading in neoadjuvant treated pancreatic cancer: an interobserver study

Area of Science:

• Oncology
• Pathology
• Gastroenterology

Background:

• Pancreatic ductal adenocarcinoma (PDAC) treatment often involves neoadjuvant chemoradiation.
• Histological regression grading is used to assess treatment response in PDAC.
• Several regression grading systems exist, but their clinical utility is debated.

Purpose of the Study:

• To evaluate the utility, reproducibility, and concordance of three common regression grading systems for neoadjuvant chemoradiation-treated PDAC.
• To identify limitations and sources of discrepancy among the College of American Pathologists (CAP), Evans, and MD Anderson Cancer Centre (MDA) systems.

Main Methods:

• Four gastrointestinal pathologists assessed 14 PDAC cases treated with neoadjuvant chemoradiation.
• The CAP, Evans, and MDA regression grading systems were applied.
• Pathologist agreement was statistically analyzed using Kendall's coefficient of concordance.

Main Results:

• Low concordance was observed across all three grading systems.
• Discrepancies arose from subjective interpretation of fibrosis and arbitrary percentage cut-offs.
• The MDA system showed higher concordance, attributed to oversimplified criteria.

Conclusions:

• The evaluated regression grading systems lack precision and clarity for accurate PDAC assessment.
• The clinical relevance of current histological regression grading in patient management is questionable.
• A need exists for a reproducible and clinically meaningful regression grading system for pancreatic cancer.