Utility of 18F-FDG PET for Predicting Histopathologic Response in Esophageal Carcinoma following Chemoradiation.

Abstract

For patients with esophageal cancer undergoing neoadjuvant chemoradiation (CRT) followed by surgical resection, complete histopathologic response (pCR) is associated with favorable overall survival (OS). The aim of this study was to evaluate the correlation between 18F-fluorodeoxyglucose positron emission tomography (FDG PET) response to neoadjuvant CRT and pCR. Maximum standardized uptake values and standardized uptake ratios (SURs) were measured before and after CRT. SUR was normalized to liver uptake and mediastinal blood pool uptake. FDG PET complete response was defined as metabolic activity normalization to hepatic and blood pool activity. The correlation between FDG PET parameters and pCR was examined through logistic regression analyses. In total, 193 patients were monitored for a median of 3.6 years after initiation of CRT. Most tumors were adenocarcinoma (85%) and stage T3 (75%). Complete FDG PET response and pCR occurred in 27% and 34% of patients, respectively. Histologic findings, chemotherapy type, tumor stage, and radiation dose were not significantly associated with complete radiographic response. The rates of pCR in patients with and without radiographic complete response were 42% and 31% (p= 0.17), respectively. No predictive correlation was found between pCR and change in maximum standardized uptake value (p= 0.25), in SUR normalized to blood pool uptake (p= 0.20), or in SUR normalized to liver uptake (p= 0.15). The 5-year OS rate was 46% for patients with a complete FDG PET response versus 44% without a complete response (p= 0.78). The 5-year OS rate of patients who achieved pCR was 49% versus 43% for patients with residual tumor (p= 0.04). For patients with esophageal cancer who received neoadjuvant chemoradiation, pretreatment and posttreatment FDG PET parameters did not correlate with pCR or OS.