Abstract
BackgroundTo evaluate the incidence of chest wall toxicity after lung stereotactic ablative radiotherapy (SABR) and identify risk factors for the development of rib fracture.MethodsThirty-nine patients with 49 lesions underwent SABR for primary or metastatic lung tumors using Cyberknife® with tumor tracking systems. Patient characteristics, treatment factors and variables obtained from dose-volume histograms (DVHs) were analyzed to find the association with chest wall toxicity. Four-dimensional (4D) dose calculations were done to investigate the effect of respiratory motion on dose to the ribs.ResultsAfter follow-up of median 26.7 months (range: 8.4 – 80.0), 8 patients (20.5%) experienced rib fractures and among these patients, three (37.5%) had chest wall pain at 2–3 months after SABR. Median time to rib fracture was 13.4 months (range: 8.0 – 38.5) and the 2-year actuarial risk of rib fracture was 12.2%. Dose to the 4.6 cc of the ribs (D4.6cc) and rib volume received 160 Gy or more (V160) were significant predictor for rib fracture. No significant differences between three-dimensional (3D) and 4D dose calculations were found.ConclusionsParameters from DVH are useful in predicting the risk of chest wall toxicity after SABR for lung tumors. Efforts should be made to reduce the risk of the rib fracture after lung SABR.
Highlights
To evaluate the incidence of chest wall toxicity after lung stereotactic ablative radiotherapy (SABR) and identify risk factors for the development of rib fracture
Excellent local control rates have been reported in stereotactic ablative body radiotherapy (SABR) for early stage lung cancer [1,2,3]
Patients We retrospectively evaluated total 44 patients who were treated with SABR for primary or metastatic lung tumors from July 2008 to October 2014 at Soonchunhyang University Seoul Hospital
Summary
To evaluate the incidence of chest wall toxicity after lung stereotactic ablative radiotherapy (SABR) and identify risk factors for the development of rib fracture. Excellent local control rates have been reported in stereotactic ablative body radiotherapy (SABR) for early stage lung cancer [1,2,3]. Based on the promising treatment outcome equivalent to surgery, SABR is considered as an alternative treatment in medically inoperable patients, and in operable patients [4,5,6]. Higher dose to the tumor improves local control rate, but at the same time, it increase the dose to the adjacent normal tissues. SABR is well tolerated and the reported incidences of acute and late toxicities are low. Use of large dose per fraction and increased survival of patients raised concerns about late toxicities different from conventional radiotherapy.
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