Ineffectiveness of ¹⁸F-fluorodeoxyglucose positron emission tomography in the evaluation of tumor response after completion of neoadjuvant chemoradiation in esophageal cancer.

Abstract

To evaluate the role of ¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) in the assessment of tumor response after the completion of neoadjuvant chemoradiation (CRT) in patients with locally advanced resectable esophageal cancer. After primary CRT, a noninvasive evaluation of the tumor response could help in the treatment decision to identify patients who may benefit from surgery. Whether FDG-PET provides clinically relevant information remains questionable. Operable patients with locally advanced esophageal cancer (clinically staged T3 N0-1 M0) were enrolled in this prospective study. The complete treatment plan included neoadjuvant CRT (cisplatin + 5-fluorouracil/45 Gy) followed 6 to 8 weeks later by a transthoracic en bloc esophagectomy. Morphological evaluation combined with FDG-PET was performed 2 weeks before the start of CRT and 4 to 6 weeks after the completion of CRT. Intratumoral pre- and posttreatment FDG-standardized uptake values (SUV1, SUV2, percentage change) were assessed. These variables were correlated with pathological and morphologic responses and survival. Investigators were blinded to the FDG-PET results unless they revealed metastatic disease. Of 60 total patients, 46 underwent the complete treatment plan (median age: 60.1 years; adenocarcinoma: 25 patients; squamous cell cancer: 21 patients). A major pathological response occurred in 45.7% of patients and was associated with a favorable outcome (P = 0.057). Neoadjuvant CRT led to a significant reduction in intratumoral FDG-uptake (P < 0.001). No significant association was seen between a pathological response (either complete or major) and the FDG-PET results (P > 0.280). The SUV2 value was correlated with a morphological response and the possibility to perform an R0 resection (P < 0.018; receiver operating characteristic curve analysis: SUV2 threshold = 5.5). No significant association was found between metabolic imaging and recurrence or survival. FDG-PET does not effectively correlate with pathological response and long-term survival in patients with locally advanced esophageal cancer undergoing neoadjuvant CRT followed by surgery. (Registered on the www.e-cancer RECF0350.).