To evaluate the treatment response of locally advanced esophageal cancer after preoperative chemoradiotherapy by FDG-PET/CT scan

Background: This study was designed to gauge the effectiveness of evaluation of tumor response and prognosis by positron emission tomography with 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) before and after preoperative chemoradiotherapy in patients with esophageal cancer.

Methods: Forty-nine patients from October 2008 to September 2012 with locally advanced stage esophageal carcinoma, clinical stage T2-4N0-3M0, who underwent preoperative chemoradiotherapy (pre-CRT) followed by esophagectomy were enrolled in our study. All patients underwent two FDG-PET scans to compare those results with the pathologic results. Metabolic response of the primary tumor by the percentage change of the SUVmax/1 hour (ΔSUV) before and after pre-CRT (ΔSUV was calculated as the difference between pre-CRT SUVmax/1 hour and post-CRT SUVmax/1 hour divided by pre-CRT SUVmax/1 hour at esophageal tumor) was evaluated for overall survival (OS), disease free survival (DFS), local recurrence rate, and distant failure free survival (DFFS). Prognostic factors such as age, different regimen of chemotherapy, pathologic stage, FDG-PET stage, endoscopic esophageal tumor length, and ΔSUV were analyzed. The number of highly suspect malignant lymph nodes was calculated by PET when SUVmax/1 hour ≥2.5 and by surgical removal. Sensitivity and specificity of regional lymph node detection by PET were also recorded.

Results: Upon univariate analysis, overall survival rate was related to ΔSUV >60% (p = 0.045), pathological N stage (p = 0.001), and endoscopic total length of esophageal tumor (p = 0.005). The result of FDG-PET scan after pre-CRT had high specificity (96.7%) but low sensitivity (45.8%) in predicting the residual malignant lymph node numbers. The positive and the negative prediction rates were 44% and 96%, respectively. The result of the FDG-PET after pre-CRT showed upstaged in 16 patients (32.6%), downstaged in nine patients (18.3%), and the same stage in 24 patients (48.9%) when compared with the pathologic stage [corrected].

Conclusion: The change of SUVmax can be a tool for evaluating tumor response after pre-CRT. There is also a trend of good prognosis in overall survival rate when ΔSUV value is >60%.