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Xingzhe Li
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P05 - Early Stage/Localized Disease - Radiotherapy (ID 114)
- Event: WCLC 2020
- Type: Posters
- Track: Early Stage/Localized Disease
- Presentations: 1
- Moderators:
- Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
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P05.10 - Risk Factors Associated with Pulmonary Toxicities from Multiple Courses of Lung Stereotactic Body Radiation Therapy (SBRT) (ID 1957)
00:00 - 00:00 | Presenting Author(s): Xingzhe Li
- Abstract
Introduction
Although lung SBRT is generally considered safe, data are limited on toxicity from multiple courses of lung SBRT in the same patient. We, therefore, examined pulmonary toxicity from multiple courses of lung SBRT in a large, modern cohort of patients.
Methods
We reviewed all patients treated with multiple courses of definitive lung SBRT without history of other lung radiation at our institution between January 2014 and October 2019. Dosimetric data were collected from composite treatment plans with deformable registration and converted to EQD2Gy. Grade ≥2 radiation pneumonitis (Gr2+RP) and grade ≥2 pulmonary toxicities (Gr2+PT) after the last course of SBRT, including dyspnea, cough, hypoxia and RP, were assessed per CTCAE v5.0. Logistic regression analyses were performed to examine correlations between patient or treatment factors and Gr2+RP or Gr2+PT.
Results
We identified 110 eligible patients (56 female and 54 male) with a median age of 74 yrs. There were 74 patients with early stage non-small cell lung cancer, whereas 36 patients had lung metastases. The percentage of patients with smoking history, pre-existing lung disease (COPD or asthma), prior lung surgery and systemic therapy within 90 days of last SBRT course were 73.6%, 43.6%, 39.1% and 18.2%, respectively.
The majority (91.8%) of patients received 2 courses of SBRT, and 9 (8.2%) received ≥3 courses. Most common SBRT regimens were 50 Gy/5 fractions (fx) (42.9%), 48 Gy/4 fx (29.4%) and 54 Gy/3 fx (20.8%), with a median BED10 of 105.6 Gy (IQR: 100-105.6). There were a similar percentage of synchronous (51.8%) and metachronous (48.2%) courses. The median composite lung V20, lung V5 and MLD in EQD2Gy were 12.7% (IQR:9.9-16.0%), 28.3% (IQR: 22.1-34.8%) and 11.2 Gy (IQR: 8.9-13.8 Gy), respectively.
With a median follow-up of 12.1 months (IQR: 7.5-23.2), 31 (28.2%) patients experienced Gr2+PT, the most common (n=21, 19.1%) being Gr2+ RP. There were 6 (5.5%) patients that developed grade 3+PT, including 3 grade 3 RP, 3 grade 3 hypoxia, 1 grade 3 dyspnea, 1 grade 3 cough, and 1 grade 4 RP, with no grade 5 pulmonary toxicities. On univariate analysis, only female gender was found to be significantly associated with Gr2+RP, whereas female gender and composite lung V20 were found to be significantly associated with Gr2+PT. On multivariate analyses, female gender (OR=3.85, p=0.025) and age >70 (OR=4.67, p=0.03) were significant for Gr2+RP, whereas female gender (OR=2.86, p=0.038), synchronous courses (OR=2.86, p=0.037) and composite V20 (OR=1.13, p=0.02) were significant for Gr2+PT. The rates of Gr2+PT above vs. below the median lung V20 were 33.3% vs. 23.2% (p=0.238).
Conclusion
Our data suggest that incidence of pulmonary toxicities with multiple courses of lung SBRT appears to be moderate, although higher than single course lung SBRT. Female gender, age>70, synchronous courses and increasing composite lung V20 may be risk factors for Gr2+ PT or Gr2+ RP. To guide clinical decisions regarding the feasibility and risks of multiple courses of SBRT, further analyses to identify cumulative dosimetric predictors and constraints for pulmonary toxicities are planned.
