March 3, 2026

“Horses out of the barn”: pancreatic ductal adenocarcinoma frequently extends beyond the grossly visible tumour, requiring microscopic rectification for accurate T‐staging

Key Points

Carcinoma often extends beyond the visible tumour mass, impacting staging accuracy.
About 16% of pT1/T2 tumours show carcinoma in peripancreatic soft tissues, mimicking pT3 behaviour.
Assessment emphasizes a qualitative method—microscopic correction—to accurately determine tumour staging.
Significantly, the orange-peeling protocol may improve the classification of tumours to ensure proper treatment planning.

Abstract

This study elucidates that PDAC frequently extends beyond the visible mass ('horses out of the barn' phenomenon); peripancreatic soft tissue involvement is common, and gross size often underestimates the true tumour extent, making microscopic correction crucial. Approximately one in six pT1/T2 tumours (≤4 cm) shows carcinoma in both anterior and posterior soft tissues and behave like pT3 in outcomes and nodal status. Therefore, gross-micro rectification is essential to avoid understaging, particularly for T2 tumours. The orange-peeling protocol should classify tumours with foci in both anterior and posterior soft tissues as pT3, while other approaches may employ mapping techniques to enable microscopic reconstruction and biologically accurate staging.

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“Horses out of the barn”: pancreatic ductal adenocarcinoma frequently extends beyond the grossly visible tumour, requiring microscopic rectification for accurate T‐staging

Key Points

Abstract

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