PS02.084: PROSPECTIVE EVALUATION OF 18F-FDG PET-CT AFTER NEOADJUVANT CHEMORADIOTHERAPY FOR DETECTING LYMPH NODE METASTASES NEAR THE CELIAC TRUNK IN PATIENTS WITH ESOPHAGEAL CANCER

Background Celiac trunk metastases are an independent factor for inferior survival in patients with esophageal cancer. Detecting these metastases before esophagostomy would aid clinical decision making. The aim of our study was to evaluate the accuracy of integrated PET and CT (PET-CT) using 18F-FDG in detecting these metastases in patients with esophageal cancer after neoadjuvant chemoradiotherapy (nCRTx) followed by esophagectomy. Methods All patients with a carcinoma of the mid-to-distal esophagus or the gastroesophageal junction (GEJ) who underwent esophageal resection with curative intent following nCRTx between January 2011 and January 2017 were included. The PET-CT scans after nCRTx were reviewed by nuclear radiologists and lymph nodes within a margin of 2 cm around the celiac trunk were expressed in SUVmax. Lymph nodes with SUVmax > 2.0 were deemed positive. The truncal nodes were extracted during esophagectomy and reviewed by different pathologists using standard pathology protocol. To assess the accuracy of the PET-CT in detecting lymph node metastases near the celiac trunk the sensitivity, specificity and positive and negative predictive value were calculated. Results A total of 448 patients were included. There were 24 patients (5.4%) with positive truncal nodes on the PET-CT versus 424 patients (90.6%) with negative truncal nodes on the PET-CT. Out of these 24 patients 20 (83.3%) had truncal node metastases confirmed in the resection specimen (positive predictive value of 83.3%). In the other 424 patients 40 (9.4%) had truncal node metastases confirmed in the resection specimen (negative predictive value of 90.6%). This results in a sensitivity of 33.3% and a specificity of 99.0%. Conclusion The sensitivity and specificity of the PET-CT in detecting lymph node metastases near the celiac trunk in patients with esophageal cancer who underwent nCRTx were respectively 33.3% and 99.0% This shows that the PET-CT is accurate in detecting truncal lymph node metastases in this patient group. Disclosure All authors have declared no conflicts of interest.