Complete pathological response (pCR) in gastroesophageal cancer: Correlation with metabolic response.

Purpose: Neoadjuvant chemoradiotherapy (nCRT) followed by surgery in patients with resectable esophageal or esophagogastric junctional (GEJ) (Siewert I) cancer is associated with long term overall survival benefits. Up to one third of all patients submitted to nCRT present pathological complete response (pCR). ¹⁸ F-fluorodeoxyglucose positron emission tomography with CT ( ¹⁸ F-FDG PET-CT) is an important tool for assessing treatment response. Purpose was to assess retrospectively the power of ¹⁸ F-FDG PET-CT in predicting pCR to evaluate the feasibility of a "watch and wait" approach.
Patients and Methods: Retrospective analysis of a prospective database with esophageal or GEJ submitted to pre-operative chemoradiation. Pre and pos treatment ¹⁸ F-FDG PET-CT were reviewed and classified using visual assessment and PERCIST criteria and the values of maximum standard uptake value were also recorded. Patients were classified as pCR or non-PCR. ¹⁸ F-FDG PET-CT and pathological findings were compared against each other.
Results: Forty-three patients were included. The median age was 67 years and 90.7% were male. All patients underwent preoperative CRT and were evaluated with ¹⁸ F-FDG PET-CT pre and post treatment. Transthoracic surgery was performed in all patients. Histological type was adenocarcinoma in 37% and squamous cell carcinoma in 58%. pCR was achieved in 56% of cases. Visual assessment of ¹⁸ F-FDG PET-CT showed overall sensitivity 57.9%, specificity 62.5% and PERCIST criteria had 100% sensibility and 16.7% specificity.
Conclusions: ¹⁸ F-FDG PET-CT is not an ideal predictor of pCR but if we use the PERCIST criteria we will have a high sensitivity and negative predictive value, avoiding false negative scans.
(Copyright © 2020 Société française de radiothérapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.)