The value of restaging CT following neoadjuvant chemotherapy for resectable gastric cancer. A population-based study

Alina Desiree Sandø,Reidun Fougner,Erling Audun Bringeland,Jon Erik Grønbech

doi:10.1186/s12957-021-02313-3

Abstract

BackgroundResponse evaluation following neoadjuvant chemotherapy (NAC) in gastric cancer is debated. The aim of this study was to investigate the value of UICC-downstaging as mode of response evaluation following a MAGIC-style regimen of NAC.MethodsRetrospective, population-based study on consecutive patients with resectable gastric adenocarcinoma receiving NAC from 2007 to 2016. CT-scan was obtained at diagnosis (rTNM) and repeated following NAC (yrTNM) to evaluate response in terms of downstaging. Further, yrTNM stage was crosstabulated to pathologic stage (ypTNM) to depict correlation between radiologic and pathologic assessment.ResultsOf 171 patients receiving NAC, 169 were available for response evaluation. For TNM-stages, 43% responded, 50% had stable disease and 7% progressed at CT. Crosstabulating yrTNM stage to ypTNM stage, 24% had concordant stages, with CT overstaging 38% and understaging 38% of the tumours, Cohen kappa ƙ = 0,06 (95%CI 0.004–0.12). Similar patterns of discordance were found for T-stages and N-stages separately. For M-category, restaging CT detected 12 patients with carcinomatosis, with an additional 14 diagnosed with carcinomatosis only at operation. No patient developed parenchymal or extra abdominal metastases, and none developed locally non-resectable tumour during delivery of NAC. Restaging CT with response evaluation was not able to stratify patients into groups of different long-term survival rates based on response mode.ConclusionsRoutine CT-scan following NAC is of limited value. Accuracy of CT staging compared to final pathologic stage is poor, and radiologic downstaging as measure of response evaluation is unreliable and unable to discriminate long-term survival rates based on response mode.

Highlights

Response evaluation following neoadjuvant chemotherapy (NAC) in gastric cancer is debated
Since the publication of the British MAGIC trial in 2006, perioperative chemotherapy has been standard of care in Europe for resectable gastric cancer [1,2,3]
For the MAGIC regimen, up to 15% experienced disease progression, even to metastatic disease, indicating that not all benefit from neoadjuvant chemotherapy (NAC) [4, 7, 10]

Summary

Introduction

Response evaluation following neoadjuvant chemotherapy (NAC) in gastric cancer is debated. The aim of this study was to investigate the value of UICC-downstaging as mode of response evaluation following a MAGIC-style regimen of NAC. Since the publication of the British MAGIC trial in 2006, perioperative chemotherapy has been standard of care in Europe for resectable gastric cancer [1,2,3]. Two principally different approaches for evaluating tumour response following NAC are available. First is histologic criteria like the Becker tumour regression grade or the Mandard score [11, 12]. Second is response evaluation by standardized CT scans before and after chemotherapy, either as UICC-downstaging or by measuring downsizing with methods like RECIST (Response Evaluation Criteria in Solid Tumours) [13]. No consensus exists on the preferred method, and implications of findings are still debated [7, 14]

Objectives

Methods

Results

Conclusion