Qualitative assessment of response to chemo-radiation with FDG-PET imaging in patients with esophageal cancer

1629 Objectives: The incorporation of 18F-FDG PET in the assessment of patients with esophageal cancer has been reported with mixed results. Post-chemo-radiation esophagitis can hinder non-invasive attempts to evaluate tumor response. This study is to compare qualitative assessment of PET response after chemoradiation to pathologic complete response (pCR) in patients undergoing chemo-radiation prior to surgery. Methods: Patients with locally advanced esophageal carcinoma undergoing pre-operative or definitive chemo-radiation underwent pre- and post-treatment 18F-FDG PET scans. The maximum SUV was measured in the tumor before chemo-radiation and 3-4 weeks after chemo-radiation (preoperatively). The post-chemo-radiation PET scans were reviewed to grade PET uptake in the esophagus without knowledge of pathologic complete response (pCR). Uptake was graded visually into 3 groups: 1. Diffuse which is mild to moderate intensity with lengthy involvement of the esophagus, 2. Diffuse with Focal spot, and 3. Focal which is mainly intense uptake and very short in length. Results: Seventy-nine patients underwent 18F-FDG PET scans during the course of treatment of esophageal malignancies between 7/02 and 12/06. Thirty-eight patients underwent esophagectomy with pathology results. All patients received chemotherapy and radiation with a median dose of 4500 cGy. The pathologic complete response was 28.9%. The pre-chemo-radiation PET scan was interpreted as 33 Focal, 3 Diffuse with Focal spot, and 1 Diffuse. The post-chemoradiation PET scan was interpreted as 28 Diffuse, 6 Diffuse with Focal spot, and 3 Focal. All nine patients with interpretation of focal involvement post therapy did not have a pCR. The qualitative interpretation of focal involvement is high for specificity and positive predictive value. Conclusions: Qualitative PET imaging was specific for predicting residual tumor in patients with esophageal cancer after chemo-radiation. Qualitative assessment of PET response should be included in future models to predict pCR in patients with esophageal cancer treated with chemo-radiation. Research Support (if any): None