(S038) Pulmonary Dose-Volume Predictors of Radiation Pneumonitis Following Stereotactic Body Radiation Therapy

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Article
OncologyOncology Vol 29 No 4_Suppl_1
Volume 29
Issue 4_Suppl_1

Symptomatic RP occurred in 23.1% of our patients treated with SBRT. Lung V10 was the strongest predictor of grade ≥ 2 RP on multivariate logistic regression, associated with a 30% decrease in risk for patients with V10 < 10.9 Gy compared with ≥ 10.9 Gy. Further research is needed to validate these findings and the importance of lung V10 in predicting symptomatic RP following SBRT.

Eileen M. Harder, BS, Henry S. Park, MD, MPH, Zhe Chen, PhD, FAAPM, Roy H. Decker, MD, PhD; Department of Therapeutic Radiology, Yale University School of Medicine

PURPOSE: Radiation pneumonitis (RP) can be a significant risk after stereotactic body radiation therapy (SBRT). The purpose of this study was to identify clinical and dosimetric predictors of symptomatic (grade ≥ 2) RP following pulmonary SBRT.

MATERIALS AND METHODS: Patients with ≥ 3 months of follow-up who received SBRT for primary lung cancer were selected from an institutional database. RP was determined retrospectively from all available records, including those from appointments with radiation oncology, pulmonology, and medical oncology and hospitalizations. RP was scored per Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0). Normal lung volume was defined as total lung volume minus gross tumor volume (GTV) on the planning computed tomography (CT). Pulmonary Dmax (maximum point dose), mean lung dose (MLD), and Vx (volume of lung receiving ≥ x Gy) in 5-Gy increments were collected. Univariate analyses were performed with the chi-square or Student’s t-test. Dosimetric predictors of RP were identified using multivariate logistic regression with a manual forward stepwise selection technique.

RESULTS: A total of 264 patients were included (median follow-up 29.4 mo). Median prescription dose was 54 Gy (range: 40–60 Gy). Patient characteristics were as follows: 27 (10.2%) had multifocal disease, 58 (22.0%) had T-stage ≥ 2, 26 (9.8%) had prior lung radiotherapy (4.2% with SBRT), and 72 (27.3%) had prior lung resection. Grade ≥ 2 RP occurred in 61 patients (23.1%) with a median onset time of 1.8 months (range: 0.1–16.2 mo). Grade ≥ 3 RP occurred in 23 patients (8.7%). Lung V5, V10, V15, V20, V25, V30, V35, V40, V45, and MLD were significantly associated with grade ≥ 2 RP on univariate analysis (P < .05), but no correlation was seen with lung V50, lung Dmax, age, gender, Eastern Cooperative Oncology Group (ECOG) performance status, cigarette use, T stage, location (central/peripheral), lobe (upper/lower) synchronicity, prescribed BED, GTV, ITV, PTV, pretreatment pulmonary comorbidity, or any heart dosimetric volume. Among these significant factors, lung V10 was the strongest predictor of RP on multivariate analysis (P = .006). The median lung V10 was 10.9 Gy. Symptomatic RP was present in 18.9% of patients receiving lung V10 < 10.9 Gy, compared with 27.3% with lung V10 ≥ 10.9 Gy.

CONCLUSIONS: Symptomatic RP occurred in 23.1% of our patients treated with SBRT. Lung V10 was the strongest predictor of grade ≥ 2 RP on multivariate logistic regression, associated with a 30% decrease in risk for patients with V10 < 10.9 Gy compared with ≥ 10.9 Gy. Further research is needed to validate these findings and the importance of lung V10 in predicting symptomatic RP following SBRT.

Proceedings of the 97th Annual Meeting of the American Radium Society - americanradiumsociety.org

Articles in this issue

(P005) Ultrasensitive PSA Identifies Patients With Organ-Confined Prostate Cancer Requiring Postop Radiotherapy
(P001) Disparities in the Local Management of Breast Cancer in the United States According to Health Insurance Status
(P002) Predictors of CNS Disease in Metastatic Melanoma: Desmoplastic Subtype Associated With Higher Risk
(P003) Identification of Somatic Mutations Using Fine Needle Aspiration: Correlation With Clinical Outcomes in Patients With Locally Advanced Pancreatic Cancer
(P004) A Retrospective Study to Assess Disparities in the Utilization of Intensity-Modulated Radiotherapy (IMRT) and Proton Therapy (PT) in the Treatment of Prostate Cancer (PCa)
(S001) Tumor Control and Toxicity Outcomes for Head and Neck Cancer Patients Re-Treated With Intensity-Modulated Radiation Therapy (IMRT)-A Fifteen-Year Experience
(S003) Weekly IGRT Volumetric Response Analysis as a Predictive Tool for Locoregional Control in Head and Neck Cancer Radiotherapy 
(S004) Combination of Radiotherapy and Cetuximab for Aggressive, High-Risk Cutaneous Squamous Cell Cancer of the Head and Neck: A Propensity Score Analysis
(S005) Radiotherapy for Carcinoma of the Hypopharynx Over Five Decades: Experience at a Single Institution
(S002) Prognostic Value of Intraradiation Treatment FDG-PET Parameters in Locally Advanced Oropharyngeal Cancer
(P006) The Role of Sequential Imaging in Cervical Cancer Management
(P008) Pretreatment FDG Uptake of Nontarget Lung Tissue Correlates With Symptomatic Pneumonitis Following Stereotactic Ablative Radiotherapy (SABR)
(P009) Monte Carlo Dosimetry Evaluation of Lung Stereotactic Body Radiosurgery
(P010) Stereotactic Body Radiotherapy for Treatment of Adrenal Gland Metastasis: Toxicity, Outcomes, and Patterns of Failure
(P011) Stereotactic Radiosurgery and BRAF Inhibitor Therapy for Melanoma Brain Metastases Is Associated With Increased Risk for Radiation Necrosis
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