Preoperative Imaging Evaluation after Downstaging of Pancreatic Ductal Adenocarcinoma: A Multi-Center Study.

Alessandro Beleù,Paolo Tinazzi Martini,Giovanni Marchegiani,Giulio Rizzo,Aldo Scarpa,Claudio Bassi,Mirko D’Onofrio,Riccardo De Robertis,Roberto Calbi,Roberto Salvia,Nicolò Bellini,Simona Caloggero,Paola Capelli,Angela Calabrese,Giovanni Carbognin

doi:10.3390/cancers11020267

Abstract

Introduction: Evaluation of pancreatic ductal adenocarcinoma (PDAC) after chemoradiotherapy downstaging is challenging due to computed tomography (CT) overestimation of tumor extension and residual vascular involvement, limiting access to surgery to some patients with potentially resectable tumors. With this study, we wanted to assess which radiological findings are most reliable at pre-operative imaging in the evaluation of PDAC after chemoradiotherapy in order to achieve complete resection. Methods: We retrospectively enrolled 71 patients with locally advanced and borderline resectable PDAC who underwent neoadjuvant chemoradiotherapy. Pre-operative CT or magnetic resonance (MR) have been evaluated by three radiologists to assess major qualitative and quantitative parameters of lesions. Accuracy, sensitivity, and specificity compared to anatomopathological results were evaluated for each parameter. Cohen’s K-coefficient has been calculated to evaluate the inter-observer agreement (IOA). Both single and consensus lecture have been tested. Different dimensional cut-offs were tested to categorize tumors according to their major axis and to compare with anatomopathological diameter, tumor persistence, and margin infiltration. Results: A 25 mm cut-off was 67% sensitive, 90% specific, and 77% accurate in assessing real tumor dimension. 25 mm cut-off reported a 64% sensitivity, 78% specificity, and 69% accuracy in assessing R0 resection. Each 5 mm increment of major axis dimension there is an odds ratio (OR) 1.79 (95% CI 1.13–2.80, p = 0.012) for R+ resection. Imaging presence of the perivascular cuff is not associated with tumor persistence and resection margin infiltration (p = 0.362). Lesion enhancement and pattern homogeneity were not accurate in determining tumor persistence. IOA was generally poor to fair, except for >25 mm cut-off classification where IOA was moderate. Diagnostic accuracy is superior in consensus lecture rather than single lecture. Conclusion: Imaging methods tend to underestimate PDAC resectability after neoadjuvant-CRT. IOA is poor to fair in evaluating most of the qualitative parameters of downstaged pancreatic adenocarcinoma. Surgery should be considered for downstaged borderline resectable PDACs, independently from perivascular cuff presence, especially for tumors smaller than 25 mm.

Highlights

Evaluation of pancreatic ductal adenocarcinoma (PDAC) after chemoradiotherapy downstaging is challenging due to computed tomography (CT) overestimation of tumor extension and residual vascular involvement, limiting access to surgery to some patients with potentially resectable tumors
78.9% of patients have been studied with CT, 21.1% with magnetic resonance (MR), while 45.1% of patients received FOLFIRINOX CRT, 32.4% Gemcitabine-Abraxane, 2.8% FOLFIRINOX-radiotherapy, 2.8% Gemcitabine-Abraxane-radiotherapy, and 16.9% received a combination of previous mentioned chemotherapeutic agents
The overestimation is due to multiple factors, in particular to the presence of peripancreatic edema and fibrosis induced by CRT, which can mimic a residual tumor

Summary

Introduction

Evaluation of pancreatic ductal adenocarcinoma (PDAC) after chemoradiotherapy downstaging is challenging due to computed tomography (CT) overestimation of tumor extension and residual vascular involvement, limiting access to surgery to some patients with potentially resectable tumors. Results: A 25 mm cut-off was 67% sensitive, 90% specific, and 77% accurate in assessing real tumor dimension. Radiological assessment of residual PDAC after neoadjuvant CRT represents one of the major radiological challenges in pancreatic cancer management [12]. It has long been known that computed tomography (CT), despite being the method of choice for the staging of PDAC, tends to be less accurate in the evaluation of the effective post-CRT resectability, reporting an overestimation of real tumor extension in most of the studies [13,14,15]. After CRT, tumor cell numbers may be reduced, but the preexisting fibrous matrix persists, with the eventual addition of further fibrosis and a variable quote of perilesional edema, mimicking pathologic tumor tissue persistence [16]

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Discussion

Conclusion