Regression grading in neoadjuvant treated pancreatic cancer: an interobserver study.
OBJECTIVE
Several regression grading systems have been proposed for neoadjuvant chemoradiation-treated pancreatic ductal adenocarcinoma (PDAC). This study aimed to examine the utility, reproducibility and level of concordance of three most frequently used grading systems.


METHODS
Four gastrointestinal pathologists used the College of American Pathologists (CAP), Evans, MD Anderson Cancer Centre (MDA) regression grading systems to grade 14 selected cases (7-20 slides from each case) of neoadjuvant chemoradiation-treated PDAC. A postscoring discussion with each pathologist was conducted. The results were entered into a standardised data collection form and statistical analyses were performed.


RESULTS
There was little concordance across the three systems. The Kendall coefficient of concordance agreement scores were: CAP: 2-poor, 2-fair; Evans: 1-fair, 1-moderate, 2-good; MDA: 1-poor, 2-moderate, 1-good. Interpretation in all three grades in the CAP grading system was a source of discrepancy. Furthermore, using fibrosis as a criterion to assess regression was contentious. In the Evans system, quantifying tumour destruction using arbitrary percentage cut-offs (ie, 9% vs 10%; 50% vs 51%, etc) was imprecise and subjective. Although the MDA system generated greatest concordance, this was due to 'oversimplification' surrounding wide, arbitrarily assigned thresholds of </> 5% of tumour.


CONCLUSIONS
All systems lacked precision and clarity for accurate regression grading. Presently the clinical utility and impact of histological regression grading in patient management is questionable. There is a need to re-evaluate regression grading in the pancreas and establish a reproducible, clinically relevant grading system.
Laboratory Medicine Program, Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Sangeetha
S
N Kalimuthu
Laboratory Medicine Program, Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Stefano
S
Serra
Laboratory Medicine Program, Department of Medical Oncology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Neesha
N
Dhani
Laboratory Medicine Program, Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Sara
S
Hafezi-Bakhtiari
Laboratory Medicine Program, Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Eva
E
Szentgyorgyi
Laboratory Medicine Program, Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Rajkumar
R
Vajpeyi
Laboratory Medicine Program, Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Runjan
R
Chetty
D000368:Aged; D021441:Carcinoma, Pancreatic Ductal / Q000473:pathology* / Q000628:therapy; D059186:Chemoradiotherapy, Adjuvant; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D060787:Neoplasm Grading / Q000379:methods* / Q000592:standards; D015588:Observer Variation; D010190:Pancreatic Neoplasms / Q000473:pathology* / Q000628:therapy
CANCER; HISTOPATHOLOGY; NEOPLASMS; ONCOLOGY; PANCREATIC CANCER