Impact of toxicity grade and scoring system on the relationship between mean lung dose and risk of radiation pneumonitis in a large cohort of patients with non-small cell lung cancer.
OBJECTIVE
To compute the risk of radiation pneumonitis (RP) as a function of mean lung dose (MLD), with RP scored using three grading systems and analyzed at four threshold levels of toxicity in a large cohort of patients with non-small cell lung cancer (NSCLC) treated with definitive radiotherapy (RT).


METHODS
On the basis of medical records and radiographic images, RP was scored retrospectively in 442 patients with NSCLC who had >or=6 months of follow-up after the end of RT. The severity of RP was scored for each patient using the National Cancer Institute (NCI) Common Toxicity Criteria, version 2.0 (CTC2.0); the NCI Common Terminology Criteria for Adverse Events, version 3.0 (CTCAE3.0); and the grading system of the Radiation Therapy Oncology Group (RTOG). For each grading system and for each of four levels of toxicity (Grade >or=1, >or=2, >or=3, >or=4), the Lyman, logistic, and log-logistic normal tissue complication probability (NTCP) models were fitted to the data as functions of MLD. The parameter estimates from the model fits are listed in table form, and the RP risk estimates are presented graphically for the Lyman and log-logistic NTCP models.


RESULTS
The results presented here illustrate the impact of scoring system and level of toxicity on the relationship between MLD and RP risk.


CONCLUSIONS
These results facilitate quantitative comparisons between our data and studies of RP risk reported by others, and several examples of such comparisons are provided.
Tucker
Susan L
SL
Department of Bioinformatics and Computational Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77230-1402, USA. sltucker@mdanderson.org
Jin
Hekun
H
Wei
Xiong
X
Wang
Shulian
S
Martel
Mary K
MK
Komaki
Ritsuko
R
Liu
H Helen
HH
Mohan
Radhe
R
Chen
Yuhchyau
Y
Cox
James D
JD
Liao
Zhongxing
Z
D000465:Algorithms; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D005500:Follow-Up Studies; D006801:Humans; D008168:Lung / Q000528:radiation effects*; D008175:Lung Neoplasms / Q000532:radiotherapy*; D017564:Radiation Pneumonitis / Q000209:etiology* / Q000473:pathology; D011879:Radiotherapy Dosage; D018570:Risk Assessment; D013997:Time Factors