Predictive factors for radiation pneumonitis in lung cancer treated with helical tomotherapy.
OBJECTIVE
Predictive factors for radiation pneumonitis (RP) after helical tomotherapy (HT) may differ from those after linac-based radiotherapy. In this study, we identified predictive factors for RP in patients with lung cancer treated with HT.


METHODS
We retrospectively analyzed clinical, treatment-related and dosimetric factors from 31 patients with lung cancer treated with HT. RP was graded according to Common Terminology Criteria for Adverse Events version 4.0 and grade ≥2 RP was defined as a RP event. We used Kaplan-Meier methods to compute the actuarial incidence of RP. For univariate and multivariate analysis, the log-rank test and the Cox proportional regression hazard model were used. We generated receiver-operating characteristics (ROC) curves to define the cutoff values for significant parameters.


RESULTS
The median follow-up duration was 6.6 months (range, 1.6 to 38.5 months). The 2-, 4-, and 6-month actuarial RP event rates were 13.2%, 58.5%, and 67.0%, respectively. There was no grade 4 or more RP. Ipsilateral V5, V10, V15, and contralateral V5 were related with RP event on univariate analysis. By multivariate analysis, ipsilateral V10 was factor most strongly associated with RP event. On the ROC curve, the cutoff values of ipsilateral V5, V10, V15, and contralateral V5 were 67.5%, 58.5%, 50.0%, and 55.5%, respectively.


CONCLUSIONS
In our study, ipsilateral V5, V10, V15, and contralateral V5 were significant predictive factors for RP after HT.
Department of Radiation Oncology, Kyung Hee University Medical Center, Kyung Hee University School of Medicine, Seoul, Korea.
Youngkyong
Y
Kim
Department of Radiation Oncology, Kyung Hee University Medical Center, Kyung Hee University School of Medicine, Seoul, Korea.
Seong Eon
SE
Hong
Department of Radiation Oncology, Kyung Hee University Medical Center, Kyung Hee University School of Medicine, Seoul, Korea.
Moonkyoo
M
Kong
Department of Radiation Oncology, Kyung Hee University Medical Center, Kyung Hee University School of Medicine, Seoul, Korea.
Jinhyun
J
Choi
Intensity-modulated radiotherapy; Lung neoplasms; Radiation pneumonitis; Risk factor