Role of Repeat 18F-Fluorodeoxyglucose Positron Emission Tomography Examination in Predicting Pathologic Response Following Neoadjuvant Chemoradiotherapy for Esophageal Adenocarcinoma.

Abstract

Predicting complete pathologic response (CPR) preoperatively can significantly affect surgical decision making. There are conflicting data regarding positron emission tomography computed tomography (PET CT) characteristics and the ability of PET CT to predict pathologic response following neoadjuvant chemoradiotherapy in esophageal adenocarcinoma because most existing studies that include squamous histology have limited numbers and use nonstandardized PET CT imaging. To determine if PET CT characteristics are associated with CPR in patients undergoing trimodality treatment for esophageal adenocarcinoma. A retrospective medical record review was conducted at a large tertiary cancer center from a prospectively maintained database from January 1, 2005, to December 31, 2012. Inclusion criteria were patients undergoing esophagectomy for locally advanced esophageal adenocarcinoma post-neoadjuvant chemoradiotherapy with 2 standardized PET CT studies done at our institution (pre-neoadjuvant chemoradiotherapy and post-neoadjuvant chemoradiotherapy) for review. Data collected included clinical, pathologic, imaging, and treatment characteristics. The primary study outcome was the association of PET CT characteristics with histologic confirmed pathologic response. Of the total participants, 77 patients met the inclusion criteria. Twenty-two patients (28.6%) had CPR vs 55 patients (71.4%) who had incomplete pathologic response. The 2 groups were similar in age, sex, race/ethnicity, comorbid conditions, Eastern Cooperative Oncology Group status, tumor grade, chemotherapy, and radiation regimen and days between the 2 PET CTs. The mean prestandardized uptake variable (SUV; 14.5 vs 11.2; P = .05), δ SUV (10.3 vs 5.4; P = .02), and relative δ SUV (0.6 vs 0.4; P = .02) were significantly higher in those with CPR vs incomplete pathologic response. Using the Youden Index, a δ SUV value less than 45% was predictive of residual disease with a positive predictive value of 91.7% (95% CI, 73-99; P < .05). To our knowledge, this is the largest study examining the role of PET CT characteristics in esophageal adenocarcinoma for patients undergoing neoadjuvant chemoradiotherapy that demonstrates that δ SUV of less than 45% is associated with patients with residual disease but not CPR. Based on the findings from our study, the current recommendation is still surgical resection regardless of the posttherapy PET SUV in the primary tumor. However, our study highlights the ability to detect patients with residual disease and the need to critically evaluate these patients for consideration of additional therapies.