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TU_24_3554 - Esophagitis in Patients Treated With Thoracic Stereotactic Ablative Radiation Therapy (SABR) to Tumors within 2 Cm of the Esophagus

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Esophagitis in Patients Treated With Thoracic Stereotactic Ablative Radiation Therapy (SABR) to Tumors within 2 Cm of the Esophagus
Q. Sodji1, R. Ko2, K. Bush2, M. S. Binkley1, W. Pickthorn1, P. G. Maxim2, M. F. Gensheimer3, M. Diehn2, and B. W. Loo Jr2; 1Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 2Stanford Cancer Institute, Stanford, CA, 3Department of Radiation Oncology, Stanford Cancer Institute, Stanford, CA

Purpose/Objective(s): Stereotactic ablative radiotherapy (SABR) is an important treatment modality for lung tumors. Esophageal toxicity has been a concern for centrally located tumors abutting or near the esophagus. We evaluated factors associated with development of esophageal toxicity in patients treated with SABR for tumors close to the esophagus at our institution.

Materials/Methods: We performed a retrospective review of patients treated with SABR for primary lung tumors and metastatic lesions to the lung at our institution from 2008 to 2017. We evaluated the esophageal toxicity of patients whose tumor came within 2 cm of the esophagus and whose esophagus received at least 80% of the prescribed dose. We used the Common Terminology Criteria for Adverse Events (CTCAE), version 4.0 to evaluate esophageal toxicity. The minimum distance between the tumor and the esophagus was measured in the treatment planning system.

Results: We identified 15 patients, 10 treated for lung primary tumors and 5 for metastatic tumors. Patient characteristics included a median age of 70 years (25-93 years), 8 males (53%). Six (40%) patients had a tumor abutting the esophagus, 5 (33%) had tumor ≤0.5 cm, 3 (20%) had tumor between 0.51 and 1 cm and 1 (7%) had tumor between 1 and 2 cm. The doses used included 27 Gy in 3 fractions (BED10=51.3 Gy) (1 patient), 35 Gy in 5 fractions (BED10=59.5 Gy) (2 patients), 40 Gy in 4 fractions (BED10=80 Gy) (7 patients), 45 Gy in 5 fractions (BED10=85.5 Gy) (1 patient), 50 Gy in 5 fractions (BED10=100 Gy) (3 patients) and 60 Gy in 8 fractions (BED10=105 Gy) (1 patient). Median follow-up was 4 months (2-20 months). Seven (47%) patients developed grade 2 esophagitis (symptomatic, altered eating/swallowing), all of which was temporary. No patients had grade 3 esophagitis (severely altered eating/swallowing requiring feeding tube or parenteral nutrition) or higher. No esophagitis was reported during treatment and median time to symptoms was 10 days (range 7-14 days) after SABR. Four out of 6 (67%) patients with tumor abutting the esophagus developed esophagitis, compared to 2 out of 5 (40%), 1 out of 3 (33%) and none with tumor located within 0.5 cm, between 0.51-1 cm and 1.1-2 cm respectively. Among patients treated with a BED10 of 80 Gy or less, 3 out of 10 developed esophagitis, 2 who received chemotherapy within 1-4 weeks before radiation therapy. Four out of 5 patients treated with a BED10 > 80 Gy developed esophagitis regardless of receiving chemotherapy shortly before radiation therapy.

Conclusion: Using the SABR regimens and dose gradients employed at our institution for tumors abutting or near the esophagus, we observed no severe esophageal toxicity. Temporary symptomatic esophagitis appeared to be more frequent for tumors abutting the esophagus. Few patients receiving a BED10 of 80 Gy or less experienced symptomatic esophagitis, especially if they did not receive chemotherapy within 1-4 weeks before radiation.

Author Disclosure: Q. Sodji: None. R. Ko: None. K. Bush: None. M.S. Binkley: None. P.G. Maxim: None. M.F. Gensheimer: None. M. Diehn: Employee; Kaiser Permanente. Consultant; Roche. Stock; CiberMed. B.W. Loo: Research Grant; RaySearch, Varian Medical Systems Inc. Stock; TibaRay, Inc. Vice-chair; National Comprehensive Cancer Network. Chair; American College of Radiology. Board Member; TibaRay, Inc.

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