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MA05 - Improving Outcomes in Locoregional NSCLC II (ID 901)
- Event: WCLC 2018
- Type: Mini Oral Abstract Session
- Track: Treatment of Locoregional Disease - NSCLC
- Presentations: 1
- Coordinates: 9/24/2018, 13:30 - 15:00, Room 105
MA05.06 - Locally Advanced Lung Cancer Radiotherapy in Deep Inspiration Breath Hold: Dosimetric Benefits from a Prospective Trial (ID 12465)
14:05 - 14:10 | Presenting Author(s): Mirjana Josipovic
Radiotherapy for locally advanced non-small cell lung (NSCLC) cancer is often complicated by treatment-related toxicity. A toxicity-reducing technique is deep inspiration breath hold (DIBH), where the lungs inflate and the heart is pushed downwards. DIBH is widely applied in breast radiotherapy, but only sporadically in NSCLC. We initiated the INHALE trial, investigating compliance and benefits of DIBH for NSCLC at a single academic institution.a9ded1e5ce5d75814730bb4caaf49419 Method
Patients referred for definitive radiotherapy of locally advanced NSCLC (66Gy/33 fractions) were included from May 2015-Dec 2017. All patients underwent respiratory coaching for voluntary visually guided DIBH and were imaged with PET/CT, 4D-CT and DIBH-CT. Target volumes were defined according to national guidelines. PTV margins were patient- and modality-specific. For all patients, FB and DIBH plans were made with volumetric modulated arc therapy, with equal PTV coverage. The plan with the lowest lung and/or heart dose was chosen for treatment. Normal tissue complication probability for pneumonitis was calculated retrospectively based on a logistic dose response model.4c3880bb027f159e801041b1021e88e8 Result
The treatment intent was maintained in 69 of included 88 patients (2 were downstaged, 12 upstaged, 2 withdrew consent, other causes in 3). 62/69 were DIBH compliant and in 61 patients a FB and a DIBH plan were made (in one patient, 4DCT image quality was not sufficient). In 54/61 patients, the DIBH plan was chosen for treatment. 3/54 patients lost DIBH compliance within the first few fractions.
All data is presented as median (range), with p<0.001 (Wilcoxon signed rank). Lung volume increased in DIBH by 55% (20-168%). Compared to FB, DIBH reduced mean lung dose from 14.4Gy (1.2-25.3Gy) to 11.8Gy (1.0-20.4Gy), and lung V20 from 23.7% (1.5-47.8%) to 20.8% (1.2-39.7%). Reduced lung dose translated to reduced pneumonitis risk: from 8.6% (2.3-23.3%) to 6.5% (2.2-14.4%). Lung dose constraints were violated in 5/62 patients in FB and 1/62 patients in DIBH.
Mean heart dose was reduced from 3.6Gy (0.1-25.8Gy) in FB to 2.4Gy (0.1-25.3Gy) in DIBH. DIBH reduced mean heart dose in 44/61 patients. The differences between FB and DIBH varied between – 6.6Gy and 8.9Gy, stressing the influence of tumour location on the potential of reducing heart dose with DIBH.8eea62084ca7e541d918e823422bd82e Conclusion
Benefits of changed anatomy with DIBH were reduced dose to lungs and, for most patients, to the heart. Curative treatment intent could be maintained in more patients. Risk of developing radiation pneumonitis was reduced. Continuous follow up of INHALE patients will reveal how the reduced risk is manifested clinically.6f8b794f3246b0c1e1780bb4d4d5dc53
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