title: Tumor volume-adapted dosing in stereotactic ablative radiotherapy of lung tumors.
abstract: OBJECTIVE
  Current stereotactic ablative radiotherapy (SABR) protocols for lung tumors prescribe a uniform dose regimen irrespective of tumor size. We report the outcomes of a lung tumor volume-adapted SABR dosing strategy.
  
  
  METHODS
  We retrospectively reviewed the outcomes in 111 patients with a total of 138 primary or metastatic lung tumors treated by SABR, including local control, regional control, distant metastasis, overall survival, and treatment toxicity. We also performed subset analysis on 83 patients with 97 tumors treated with a volume-adapted dosing strategy in which small tumors (gross tumor volume <12 mL) received single-fraction regimens with biologically effective doses (BED) <100 Gy (total dose, 18-25 Gy) (Group 1), and larger tumors (gross tumor volume ≥12 mL) received multifraction regimens with BED ≥100 Gy (total dose, 50-60 Gy in three to four fractions) (Group 2).
  
  
  RESULTS
  The median follow-up time was 13.5 months. Local control for Groups 1 and 2 was 91.4% and 92.5%, respectively (p = 0.24) at 12 months. For primary lung tumors only (excluding metastases), local control was 92.6% and 91.7%, respectively (p = 0.58). Regional control, freedom from distant metastasis, and overall survival did not differ significantly between Groups 1 and 2. Rates of radiation pneumonitis, chest wall toxicity, and esophagitis were low in both groups, but all Grade 3 toxicities developed in Group 2 (p = 0.02).
  
  
  CONCLUSIONS
  A volume-adapted dosing approach for SABR of lung tumors seems to provide excellent local control for both small- and large-volume tumors and may reduce toxicity.
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Trakul
authors.forename: Christine N
authors.initials: CN
authors.lastname: Chang
authors.forename: Jeremy
authors.initials: J
authors.lastname: Harris
authors.forename: Christopher
authors.initials: C
authors.lastname: Chapman
authors.forename: Aarti
authors.initials: A
authors.lastname: Rao
authors.forename: John
authors.initials: J
authors.lastname: Shen
authors.forename: Sean
authors.initials: S
authors.lastname: Quinlan-Davidson
authors.forename: Edith J
authors.initials: EJ
authors.lastname: Filion
authors.forename: Heather A
authors.initials: HA
authors.lastname: Wakelee
authors.forename: A Dimitrios
authors.initials: AD
authors.lastname: Colevas
authors.forename: Richard I
authors.initials: RI
authors.lastname: Whyte
authors.forename: Sonja
authors.initials: S
authors.lastname: Dieterich
authors.forename: Peter G
authors.initials: PG
authors.lastname: Maxim
authors.forename: Dimitre
authors.initials: D
authors.lastname: Hristov
authors.forename: Phuoc
authors.initials: P
authors.lastname: Tran
authors.forename: Quynh-Thu
authors.initials: QT
authors.lastname: Le
authors.forename: Billy W
authors.initials: BW
authors.lastname: Loo
authors.forename: Maximilian
authors.initials: M
authors.lastname: Diehn
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000601:surgery; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology / Q000601:surgery; D019583:Dose Fractionation, Radiation; D004941:Esophagitis / Q000453:epidemiology / Q000209:etiology; D005260:Female; D057918:Fiducial Markers; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D008297:Male; D017564:Radiation Pneumonitis / Q000453:epidemiology; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D012062:Relative Biological Effectiveness; D012189:Retrospective Studies; D047368:Tumor Burden