Program Information
Dose Escalated Radiation Therapy for Advanced Stage Lung Cancer
N Shusharina*, G Sharp , A Niemierko , N Choi , Massachusetts General Hospital, Department of Radiation Oncology, Boston, MA
Presentations
TH-EF-FS1-6 (Thursday, August 3, 2017) 1:00 PM - 3:00 PM Room: Four Seasons 1
Purpose: To determine the optimum treatment design to deliver radiation dose beyond 60 Gy to eradicate the tumor in locally advanced lung cancer patients by comparing an impact of dose escalation in improvement of the therapeutic ratio.
Methods: Ten patients with stages II-III inoperable NSCLC were selected for the retrospective study. The PET-defined targets were delineated by biologically-weighed regions identified on a pre-treatment 18F-FDG PET image. For each patient, a base IMRT plan to 60Gy/30fxs prescribed to the 4DCT-defined PTV was created. This plan was compared to 3 dose escalation schedules: a uniform escalation to the PTV to 70Gy/35fxs and to 74Gy/37fxs, and an escalation to the PET-defined target. The latter was planned in two steps; first a simultaneous integrated boost plan was created to 60Gy/30fxs to the PTV and 66Gy/30fxs to the boost target. Second, a sequential boost to two dose levels of 8Gy/4fxs and 10Gy/4fxs was planned to create composite plans to 74 Gy and 76 Gy respectively. The EUD for the target, spinal cord, combined lung, heart, and esophagus was compared for each plan.
Results: The median size of the boost planning volume was 12.5% (range: 9.1 – 27.9%) of the PTV. The most dose-limiting plan constraints were the V60,65,70 and Dmax of the esophagus. The EUD within the boost target calculated from the composite 74 and 76Gy plans was higher than EUD within the PTV calculated from uniform escalation 74Gy plans. EUD for the organs at risk calculated from the composite plans were comparable with EUD calculated from 60Gy plan and were lower than EUD calculated from 70Gy and 74Gy plans.
Conclusion: Combination of biologically-weighted target that is smaller than PTV and hypo-fractionation regimen allows delivering 76Gy to the most aggressive part of the tumor and gaining a therapeutic ratio that is optimum for advanced NSCLC.
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