Use of increase in esophageal FDG SUV during radiotherapy to predict radiation esophagitis.

e17509 Background: Esophageal uptake of FDG is commonly seen in patients with non-small cell lung cancer (NSCLC), but the relationship of the uptake to radiation esophagitis has not been delineated. Since esophageal mucosa is sensitive to the effect of radiation, we hypothesized that: (1) esophageal FDG activity changes during fractionated radiotherapy (RT), (2) these changes are associated with radiation esophagitis. Methods: Patients with stage I-III NSCLC were prospectively enrolled and received >60 Gy RT. FDG-PET/CT scans were acquired prior to and during RT after the delivery of 45 Gy. Normalized standardized uptake values (NSUV), defined by the esophageal maximum SUV relative to intravascular background within the aortic arch, were measured at the levels of the primary tumor, sternal notch, aortic arch, carina, and gastro-esophageal junction. Grade ≥2 radiation esophagitis was defined as an event. Results: 16 of 50 patients had radiation esophagitis event. Clinical stage, concurrent chemotherapy, ma...