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Jonathan Wolf
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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
- Moderators:
- Coordinates: 9/24/2018, 13:30 - 15:00, Room 105
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MA05.05 - Photon-Based Cardiac Sparing Via Volumetric Modulated Arc Therapy in Thoracic Radiation Therapy for Locally Advanced Non-Small Cell Lung Cancer (ID 13419)
14:00 - 14:05 | Author(s): Jonathan Wolf
- Abstract
- Presentation
Background
Increasing radiation dose to the heart is associated with worse survival in stage III non-small cell lung cancer. Techniques to reduce the dose to the heart, including proton beam therapy (PBT), are being evaluated in ongoing clinical trials. However, advanced technologies such as PBT are not readily accessible for most patients. We therefore sought to evaluate the efficacy of volumetric modulated arc therapy (VMAT), a readily available technology in the United States, to spare cardiac substructures and determine how a cardiac optimization treatment planning algorithm influences dose distribution to other thoracic organs at risk (OARs).
a9ded1e5ce5d75814730bb4caaf49419 Method
We selected stage III non-small cell lung cancer patients who were treated at our institution with VMAT to 60 Gy in 2 Gy fractions. Cardiac substructures were retrospectively contoured, and included: valves, atrioventricular node (AVN), coronary arteries (CA), chambers, and great vessels. New radiation treatment plans were created to spare these structures while preserving planning target volume (PTV) coverage and maintaining standard dose constraints to OARs. Dosimetry variables—maximum dose (Dmax), mean dose (Dmean), and common clinically relevant dose-volume relationships—for the new cardiac-sparing radiation treatment plans were compared via paired t-test to the original radiation treatment plans.
4c3880bb027f159e801041b1021e88e8 Result
Twenty-six patients, treated from July 2013 to September 2017, were included. Statistically significant improvements were demonstrated for all cardiac structures for the new cardiac-sparing plans compared to the original plans, while maintaining appropriate lung, esophagus, and spinal cord constraints, and PTV coverage goals, as demonstrated in Table 1 (significant P-values in bold).
Table 1
8eea62084ca7e541d918e823422bd82e ConclusionDosimetry variable
Cardiac-sparing plan (mean)
Original plan (mean)
P-value*
Cardiac parameters
Heart Dmax
64.9 Gy
63.6 Gy
0.928
Heart Dmean
12.3
16.1
< 0.001
Heart V5Gy
55.4
64.1
0.003
Heart V30Gy
12.5
18.7
< 0.001
Heart V40Gy
7.9
11.5
< 0.001
Heart V45Gy
6.5
11.5
< 0.001
Heart V60Gy
2.7
3.4
0.001
Aortic valve Dmax
22.9
31.7
< 0.001
Aortic valve Dmean
11.4
31.7
< 0.001
Mitral valve Dmax
24.6
29.4
0.002
Mitral valve Dmean
11.2
16.7
< 0.001
Pulmonic valve Dmax
26.8
35.4
< 0.001
Pulmonic valve Dmean
14.1
25.1
< 0.001
Tricuspid valve Dmax
9.7
16.6
< 0.001
Tricuspid valve Dmean
5.6
10.3
< 0.001
AVN Dmax
13.4
20.4
< 0.001
AVN Dmean
8.1
14.0
< 0.001
Left main CA Dmax
26.4
38.8
< 0.001
Left main CA Dmean
16.4
30.2
< 0.001
Left anterior descending CA Dmax
27.4
34.8
< 0.001
Left anterior descending CA Dmean
14.4
22.6
< 0.001
Left circumflex CA Dmean
32.6
36.8
0.001
Left circumflex CA Dmean
19.3
26.9
< 0.001
Right CA Dmax
18.1
26.1
< 0.001
Right CA Dmean
9.4
15.7
< 0.001
Left atrium Dmax
51.8
54.8
0.091
Left atrium Dmean
17.5
21.0
< 0.001
Left ventricle Dmax
35.7
40.1
< 0.001
Left ventricle Dmean
8.3
11.3
< 0.001
Right atrium Dmax
31.4
36.1
0.004
Right atrium Dmean
11.1
13.9
< 0.001
Right ventricle Dmax
23.7
33.2
< 0.001
Right ventricle Dmean
6.9
12.2
< 0.001
Aorta Dmax
50.8
55.3
0.001
Aorta Dmean
20.4
27.9
< 0.001
Pulmonary artery Dmax
65.2
65.1
0.895
Pulmonary artery Dmean
32.3
37.9
< 0.001
Superior vena cava Dmax
47.4
51.7
0.002
Superior vena cava Dmean
29.4
33.1
0.006
Other OAR parameters
Lungs V5Gy
56.5
58.2
0.121
Lungs V20
22.4
23.3
0.083
Lungs Dmean
13.6
14.8
0.012
Spinal cord Dmax
28.0
31.1
0.013
Esophagus Dmean
21.2
22.1
0.023
PTV coverage parameters
PTV Dmax
65.5
67.2
0.189
PTV minimum dose
51.2
52.7
0.019
PTV V100%
95.2%
95.4%
0.195
Dose to the heart and cardiac substructures can be substantially lowered using a cardiac-sparing optimization algorithm with VMAT, without increasing radiation dose other thoracic OARs or compromising PTV coverage. Though time-consuming, delineation of the full complement of cardiac substructures provides an effective means of improving the quality of radiation treatment plans with readily available technologies.
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