15561 Background: The use of FDG PET scan in the management of esophageal neoplasms (EN) is subject to controversies. FMISO is a new available tracer for PET imaging targeting hypoxia. No data are available in the litterature using this tracer in EN. Because hypoxia and angiogenesis are related, we designed a feasibility study using both functional imaging of hypoxia with FMISO and biological markers of angiogenesis in esophageal cancer. Material and Methods: At present, after informed consent, 8 patients with newly diagnosed esophageal cancer have been included (8 males, 62 ± 11y). 7 patients had squamous cell esophageal carcinoma and one had an adenocarcinoma. All had advanced disease (4 stage 3, 4 stage 4) and were considered for exclusive radiochemotherapy. Before treatment, all patients underwent FDG PET and FMISO PET study. FMISO PET images were acquired 2 and 3 hours after the IV injection of a mean activity of 292 MBq of FMISO. The 2 PET investigations were performed within a mean interval of 7 days (3–13). P53, HER2, epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) expressions were assessed on blood samples and tumor samples obtained before treatment. Response to therapy was evaluated using RECIST criteria by conventional imaging performed one month after treatment. Results: All patients were FDG positive with high uptake in the primary(mean SUV=8,6).The pretherapeutic FDG SUV was 8.33 (responders) vs 9.6 (non responders). FMISO uptake was statistically lower in the primary lesion (mean SUV: 0.67). The pretherapeutic FMISO SUV was 0.56 (responders) vs 0.77 (non responders). One patient had lung and liver metastases demonstrated with FDG and FMISO. FMISO uptake was only peripheric (ring aspect) in the metastases. Results concerning correlation between FMISO uptake and angiogenesis markers (EGFR,VEGF,P53,HER2) will also be presented during the meeting. Conclusions: F MISO is a new tracer for hypoxia which could help to differenciate between responders and non responders before treatment in EN. These preliminary results are to be confirmed by this ongoing study. Grants from the French PHRC. No significant financial relationships to disclose.