Gastrointestinal Cancer

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SU_14_2142 - Clinical Outcomes Using Magnetic Resonance-Guided Stereotactic Body Radiation Therapy in Patients with Locally Advanced Cholangiocarcinoma

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Clinical Outcomes Using Magnetic Resonance-Guided Stereotactic Body Radiation Therapy in Patients with Locally Advanced Cholangiocarcinoma
E. Luterstein1, A. Raldow2, M. Cao2, J. M. Lamb2, D. Low3, M. L. Steinberg1, and P. Lee2; 1University of California, Los Angeles, Los Angeles, CA, 2Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, CA, 3David Geffen School of Medicine at UCLA, Los Angeles, CA

Purpose/Objective(s): Previous studies demonstrate that stereotactic body radiation therapy (SBRT) increases local control for cholangiocarcinoma, but gastrointestinal toxicity resulting from treatment remains a concern. Our previous published experience of 31 cholangiocarcinoma patients definitively treated with SBRT using Linac reported a median overall survival (OS) of 15.7 months, 1-year OS of 59%, and 1-year local control of 78% (Sandler, doi:10.1016/j.adro.2016.10.008). Six patients (19%) in this series suffered severe toxicities. SBRT using magnetic resonance-guided radiation therapy (MRgRT) may improve the therapeutic index of treatment for cholangiocarcinoma patients.

Materials/Methods: Seventeen consecutive patients with cholangiocarcinoma were treated with SBRT using MRgRT between May 2015 and August 2017 with a median follow-up time of 8.8 months. Twelve patients presented with extrahepatic cholangiocarcinoma and five patients with intrahepatic tumors, with two patients treated for locally recurrent cholangiocarcinoma. SBRT was administered at a median dose of 40 Gy in 5 fractions. Notably, one patient received concurrent hyperthermia, and one patient received an SBRT boost after IMRT. Clinical efficacy was retrospectively analyzed, with survival curve analysis performed by the Kaplan-Meier method; treatment toxicities were graded according to the designations outlined in the CTCAE V4.0. Acute and late toxicities were defined using a cutoff of 90 days from completion of radiation therapy.

Results: The median OS was 18.2 months, with a 1-year OS of 86.7%. The median progression-free survival (PFS) was 6.6 months, with a 1-year PFS of 41.6%. Three of the 17 patients progressed locally, yielding a median local control time of 16.2 months and 1-year local control of 80.8%. 12 of 17 patients experienced an acute grade 1 toxicity, with mild nausea and fatigue accounting for 80% of toxicities. No grade 2 acute toxicities were experienced; however, one patient suffered a grade 3 duodenal ulcer with perforation (6%). Only one patient had a latent radiation-related toxicity – grade 2 gastritis/colitis; no other latent toxicities occurred.

Conclusion: Our findings using MRgRT for cholangiocarcinoma patients demonstrate excellent overall survival while maintaining rates of local control comparable with the outcomes of our previous retrospective study of 31 cholangiocarcinoma patients using Linac-based SBRT. Treatment delivered through MRgRT resulted in one grade 3 toxicity (6%), while the Linac study determined that six patients (19%) suffered severe toxicities with the same median radiation dose and fractionation. Our clinical outcomes, coupled with a diminished toxicity profile, suggest SBRT using MRgRT is a promising new treatment approach.

Author Disclosure: E. Luterstein: None. A. Raldow: None. M. Cao: Speaker's Bureau; Viewray. J.M. Lamb: Speaker's Bureau; Viewray. D. Low: Research Grant; Varian Medican Systems Inc, Siemens. Travel Expenses; ViewRay Inc. Stock; ViewRay. M.L. Steinberg: Advisory Board; Viewray. P. Lee: Honoraria; Viewray. Commitee Co-Chair; Committee Co-Chair.

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