title: Prediction of chest wall toxicity from lung stereotactic body radiotherapy (SBRT).
abstract: OBJECTIVE
  To determine patient, tumor, and treatment factors related to the development of late chest wall toxicity after lung stereotactic body radiotherapy (SBRT).
  
  
  METHODS
  We reviewed a registry of 134 patients treated with lung SBRT to 60 Gy in 3 fractions who had greater than 1 year of clinical follow-up and no history of multiple treatments to the same lobe (n = 48). Patients were treated as per Radiation Therapy Oncology Group Protocol 0236 without specific chest wall avoidance criteria. The chest wall was retrospectively contoured. Thirty-two lesions measured less than 3 cm, and sixteen measured 3 to 5 cm. The median planning target volume was 29 cm(3).
  
  
  RESULTS
  With a median follow-up of 18.8 months, 10 patients had late symptomatic chest wall toxicity (4 Grade 1 and 6 Grade 2) at a median of 8.8 months after SBRT. No patient characteristics (age, diabetes, hypertension, peripheral vascular disease, or body mass index) were predictive for toxicity, whereas there was a trend for continued smoking (p = 0.066; odds ratio [OR], 4.4). Greatest single tumor dimension (p = 0.047; OR, 2.63) and planning target volume (p = 0.040; OR, 1.04) were correlated with toxicity, whereas distance from tumor edge to chest wall and gross tumor volume did not reach statistical significance. Volumes of chest wall receiving 30 Gy (V30) through 70 Gy (V70) were all highly significant, although this correlation weakened for V65 and V70 and maximum chest wall point dose only trended to significance (p = 0.06). On multivariate analysis, tumor volume was no longer correlated with toxicity and only V30 through V60 remained statistically significant.
  
  
  CONCLUSIONS
  Tumor size and chest wall dosimetry are correlated to late chest wall toxicity. Only chest wall V30 through V60 remained significant on multivariate analysis. Restricting V30 to 30 cm(3) or less and V60 to 3 cm(3) or less should result in a 10% to 15% risk of late chest wall toxicity or lower.
authors.affiliation: Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic, Cleveland, OH 44195, USA. stephak@ccf.org
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Stephans
authors.forename: Toufik
authors.initials: T
authors.lastname: Djemil
authors.forename: Rahul D
authors.initials: RD
authors.lastname: Tendulkar
authors.forename: Cliff G
authors.initials: CG
authors.lastname: Robinson
authors.forename: Chandana A
authors.initials: CA
authors.lastname: Reddy
authors.forename: Gregory M M
authors.initials: GM
authors.lastname: Videtic
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011336:Probability; D011832:Radiation Injuries / Q000473:pathology*; D016634:Radiosurgery / Q000009:adverse effects*; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects; D035441:Thoracic Wall / Q000528:radiation effects*; D013997:Time Factors; D047368:Tumor Burden