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Q. Diot
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P3.02 - Poster Session/ Treatment of Localized Disease – NSCLC (ID 211)
- Event: WCLC 2015
- Type: Poster
- Track: Treatment of Localized Disease - NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P3.02-036 - Predictors of Lung Fibrosis after Stereotactic Body Radiation Therapy (SBRT) for Stage I-II Non-Small Cell Lung Cancer (NSCLC) (ID 3197)
09:30 - 09:30 | Author(s): Q. Diot
- Abstract
Background:
Radiographic lung injury, fibrosis, occurs in over 50% of patients after SBRT. The purpose of this study was to evaluate clinical and dosimetric predictors of lung fibrosis after SBRT for stage I-II NSCLC
Methods:
A retrospective single institution database was examined for patients with Stage I-II NSCLC, T1-2N0, and lesions less than 5 cm treated with SBRT to 45-54 Gy in 3-5 fractions from 2010 to 2013. 4D CT imaging was used to assist with target localization and CT scans with at least 9 months of followup were rigidly registered to the planning CT scan based on common anatomical landmarks. Fibrosis volume was manually contoured. Simple and multiple linear regression were used to assess clinical and dosimetric variables under univariate and multivariate analyses.
Results:
We identified 26 patients and 27 lesions that met inclusion criteria. On UVA, increasing PTV volume, V20, and intermediate dose spillage (maximum total dose to any point 2 cm from PTV divided by dose prescribed) were significantly associated with increasing fibrosis (p<0.05). Non-significant predictors of fibrosis included patient age, pack years of smoking, COPD GOLD stage, use of ACE-I, and radiation dose to the PTV. On MVA accounting for factors significant for fibrosis (PTV volume, V20, intermediate dose spillage), only PTV volume remained significantly correlated with fibrosis volume (0.43 cm[3] increase in fibrosis for every 1 cm[3] increase in PTV, 95% CI, 0.08-0.77, p=0.02).
Conclusion:
In this analysis of predictors of fibrosis after SBRT, only increasing PTV volume was associated with increased fibrosis. We plan to utilize these results for future studies using pharmacologic strategies to decrease lung fibrosis.
