Incidence of radiation pneumonitis after thoracic irradiation: Dose-volume correlates.
OBJECTIVE
To define clinical and dosimetric parameters correlated with the risk of clinically relevant radiation pneumonitis (RP) after thoracic radiotherapy.


METHODS
Records of consecutive patients treated with definitive thoracic radiotherapy were retrospectively reviewed for the incidence of RP of Grade 2 or greater by the Common Toxicity Criteria. Dose-volume histograms using total lung volume (TL) and TL minus gross tumor volume (TL-G) were created with and without heterogeneity corrections. Mean lung dose (MLD), effective lung volume (V(eff)), and percentage of TL or TL-G receiving greater than or equal to 10, 13, 15, 20, and 30 Gy (V10-V30, respectively) were analyzed by logistic regression. Receiver operating characteristic (ROC) curves were generated to estimate RP predictive values.


RESULTS
Twelve cases of RP were identified in 92 eligible patients. Mean lung dose, V10, V13, V15, V20, and V(eff) were significantly correlated to RP. Combinations of MLD, V(eff), V20, and V30 lost significance using TL-G and heterogeneity corrections. Receiver operating characteristic analysis determined V10 and V13 as the best predictors of RP risk, with a decrease in predictive value above those volumes.


CONCLUSIONS
Intrathoracic radiotherapy should be planned with caution when using radiotherapy techniques delivering doses of 10 to 15 Gy to large lung volumes.
Schallenkamp
John M
JM
Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA.
Miller
Robert C
RC
Brinkmann
Debra H
DH
Foote
Tyler
T
Garces
Yolanda I
YI
D000368:Aged; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D017564:Radiation Pneumonitis / Q000453:epidemiology* / Q000209:etiology; D012189:Retrospective Studies; D016896:Treatment Outcome