title: Combination of longitudinal and circumferential three-dimensional esophageal dose distribution predicts acute esophagitis in hypofractionated reirradiation of patients with non-small-cell lung cancer treated in stereotactic body frame.
abstract: OBJECTIVE
  To evaluate dosimetric predictors of acute esophagitis (AE) and clinical outcome of patients with non-small-cell lung cancer (NSCLC) receiving reirradiation.
  
  
  METHODS
  Seventeen patients with NSCLC received reirradiation to the lung tumors/mediastinum, while immobilized in stereotactic body frame (SBF). CT simulation and hypofractionated three-dimensional radiotherapy were used. Two axial segments of esophagus contours merged together were defined as esophagus disc (ED). For each ED, the percentage (%) of the volume of esophageal circumference treated to % of prescribed dose (PD) was assessed. Number of EDs with 50% or any % of volume (V) of esophageal circumference receiving more than or equal to (>/=) 50%, 80%, and 100% of PD (50% V >/=50% PD; 50% V >/=80% PD; any % V >/=100% PD) were calculated. These dosimetric variables and the length of the esophagus within the radiation therapy (RT) port were correlated with AE using exact Wilcoxon test.
  
  
  RESULTS
  A median RT dose was 32 Gy with a median fraction size of 4 Gy. Eleven of 13 patients presenting with pain and/or shortness of breath had complete or partial resolution of symptoms. Median survival time from the start of reirradiation in SBF until death was 5.5 months. AE was observed in 7 patients and resolved within 3 months of RT completion. No Grade 3 or higher events were noticed. The length of the esophagus within RT port did not predict for AE (p = 0.71). However, an increased number of EDs predicted for AE for the following dosimetric variables: 50% V >/=50% PD (p = 0.023), 50% V >/=80% PD (p = 0.047), and any % V >/=100% PD (p = 0.004). Patients with at least 2 EDs receiving >/=100% PD to any % V of circumference had AE compared to those with zero EDs.
  
  
  CONCLUSIONS
  Reirradiation using hypofractionated three-dimensional radiotherapy and SBF immobilization is an effective strategy for palliation of symptoms in selected patients with recurrent NSCLC. The length of the esophagus in the RT field does not predict for AE. However, an increasing number of EDs displaying the combination of longitudinal and circumferential three-dimensional dose distribution along the esophagus is a valuable predictor for AE.
authors.affiliation: Department of Radiation Oncology, Kimmel Cancer Center of Jefferson Medical College, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA.
authors.forename: Igor M
authors.initials: IM
authors.lastname: Poltinnikov
authors.forename: Kevin
authors.initials: K
authors.lastname: Fallon
authors.forename: Yian
authors.initials: Y
authors.lastname: Xiao
authors.forename: Jay E
authors.initials: JE
authors.lastname: Reiff
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Curran
authors.forename: Maria
authors.initials: M
authors.lastname: Werner-Wasik
mesh_terms: D000208:Acute Disease; D000230:Adenocarcinoma / Q000532:radiotherapy; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy; D004941:Esophagitis / Q000209:etiology*; D004947:Esophagus / Q000000981:diagnostic imaging / Q000528:radiation effects*; D005260:Female; D006801:Humans; D007103:Immobilization / Q000295:instrumentation / Q000379:methods; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008479:Mediastinal Neoplasms / Q000532:radiotherapy; D008875:Middle Aged; D011832:Radiation Injuries / Q000150:complications*; D011859:Radiography; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D019233:Retreatment; D013238:Stereotaxic Techniques / Q000295:instrumentation