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A.M. Monjazeb
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P2.05 - Poster Session with Presenters Present (ID 463)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Radiotherapy
- Presentations: 1
- Moderators:
- Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)
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P2.05-056 - Safety of Stereotactic Body Radiotherapy for Central, Ultracentral, and Paramediastinal Lung Tumors (ID 5510)
14:30 - 14:30 | Author(s): A.M. Monjazeb
- Abstract
Background:
Prior studies describe increased toxicity following stereotactic body radiotherapy (SBRT) for central lung tumors. We report our institutional experience treating central lung tumors with SBRT, stratifying as central (C), ultracentral (UC) or paramediastinal (PM), and report toxicity for each cohort.
Methods:
The charts of all patients with centrally located lung tumors treated with SBRT Sept 2009 -June 2015 were reviewed. Eligible tumors were located within 2 cm of the proximal bronchial tree (PBT) or the planning target volume (PTV) overlapped the mediastinum. Tumors were classified as UC if the PTV overlapped the PBT or esophagus, C if located within 2 cm of the PBT, and PM if abutting the mediastinum but not meeting criteria as C. Toxicity was scored with CTCAE V1.1.
Results:
We identified 42 patients treated to 46 centrally-located lung tumors (38 primary and 8 metastases) treated to a median dose of 50 Gy (range 40-60) over 5 fractions (range 4-8). Nine tumors (19.6%) were classified as UC, 25 (54.3%) as C, and 12 (26.1%) as PM. The median follow-up for living patients was 21.4 months (range: 11.5-63.5). Crude rates of grade 3+ toxicity for patients with UC, C, and PM tumors were 22.2%, 4.3%, and 0% respectively (p=0.11). Grade 3+ toxicity included 2 cases of grade 3 post-obstructive pneumonia and one case of grade 5 respiratory failure following SBRT for an UC tumor. PBT doses for UC tumors routinely exceeded standard constraints. Key dose volume metrics for each group are outlined in Table 1.Maximum Point Dose in Gy: Median (range) Ultracentral Central Paramediastinal Proximal Bronchial Tree 58.0 (46.5-67.9) 29.1 (2.1-51.2) 15.8 (2.3-28.6) Esophagus 29.9 (11.1-41.2) 16.9 (4.3-37.9) 18.1 (9.7-33.2) Heart 29.8 (5.2-37.8) 18.4 (0.3-62.6) 20.1 (1.4-61.1) Great Vessels 59.7 (43.4-69.9) 41.1 (11.5-72.3) 51.9 (11.0-62.2) Grade 3+ Toxicity n=2 (22.2%) n=1 (4.3%) n=0 (0%)
Conclusion:
In our cohort, SBRT for UC tumors showed a trend toward increased high-grade toxicity, suggesting additional counseling regarding treatment risks for the subset of patients with UC lung tumors is warranted. Additional studies to optimize SBRT dose-fractionation schedules for patients with UC tumors are needed.
