Eligibility of patients with esophageal and gastroesophageal cancer for biology-guided radiotherapy in a retrospective cohort

e16100 Background: Biology-guided radiotherapy (BgRT) is a novel radiotherapy modality that uses real-time positron emission tomography (PET) to guide radiotherapy beamlets. The FDA recently cleared BgRT for clinical use for tumors in lung and bone using 18F FDG radiotracer. We sought to identify esophageal cancer (EC) and gastroesophageal junction cancer (GEJC) patients who may be BgRT candidates based on diagnostic FDG PET/CT imaging. Methods: Through IRB-approved extraction of patient medical record data from an institutional repository of prospectively maintained data, we verified a database of EC and GEJC patients diagnosed at a US tertiary care center between 01/01/2006 and 12/31/2013. When insufficient diagnostic clinical information was present, patients were excluded. Patient and tumor qualities were quantified and subjected to parameters of tumor diameter (≥2cm, <5cm) and maximum standardized uptake value (≥6) to observe potential characteristics of a patient population eligible for this novel BgRT mechanism. Results: Thirty patients met tumor size and FDG uptake criteria for BgRT therapy out of an overall patient cohort of 90 patients. A significantly greater proportion of patients within the BgRT-eligible cohort presented with esophageal tumors (83.3%) compared to non-eligible patients (58.3%, P=0.0177). Otherwise, there was no significant variation of patient sex, race, tumor histology, tumor stage, comorbidity score, and pre-treatment weight loss between patients eligible and not eligible for BgRT therapy. Conclusions: After applying current boundaries of tumor size and radiotracer uptake for effective BgRT intervention, we observed broad applicability of the novel treatment modality across EC/ GEJC patients of varying characteristics and tumor qualities. The high eligibility of patients with tumors located within the esophagus supports further investigation of BgRT in their management. [Table: see text]