combined risk score improves radiation pneumonitis prediction -
By Laura Cowen, medwireNews Reporter
The combination of dose-volume histogram (DVH) parameters with age and baseline lung fibrosis score creates a new predictive risk score that enhances radiation pneumonitis prediction (RP) in patients receiving concomitant chemoradiation for lung cancer non-small cell (NSCLC), the research shows.
The risk of RP, a potentially fatal dose limiting side effect of chemoradiation, is currently estimated using individual DVH parameters such as the percentage of lung volume receiving doses greater than 20 Gy (V20) and the mean lung dose (MLD), explain Kayoko Tsujino (Hyogo Cancer Center, Akashi, Japan) and colleagues.
In this study, the researchers investigated whether RP severe (grade 3 or higher) could be predicted more accurately by combining the DVH measurements with clinical factors.
They examined the medical records of 122 patients (median age 63 years, 89% men) with locally advanced NSCLC treated with chemoradiotherapy and found that, for a median of 14.6 months of follow up, 14 (11.5%) developed severe ROP.
in univariate analysis, the total lung volume, V5, V20, absolute lung volume spared a dose of 5 Gy (VS5), MLD, sex and pulmonary fibrosis on CT baseline were significantly associated to severe RP. Age and smoking showed a significant association limit.
In multivariate analysis, a VS5 less than 1500 cc, pulmonary fibrosis score from baseline of 2 or more, V20 of at least 26% to the age of 68 years or more were significant predictors severe RP.
based on the coefficient beta multivariate analysis, these four variables were assigned a score of 6, 5, 3 and 3, respectively, to create a predictive risk score combined (PRS).
Tsujino and team report that the cumulative incidence of severe RP to 12 months was 0%, 7.8%, 26.6% and 71.4% when the PRS was 0, 3-5, 6-8 and 9-14, respectively. No patient had a PRS score above 14.
In addition, the PRS predicted severe RP with more precision than V20 and VS5 combined, or V20 alone, with respective areas under the ROC curve of 0.888 against 0.779 and 0.678.
"Currently, we recommend that PRS should be less than eight and V20 dose constraint should be less than 30-35% in the final administration [concurrent chemoradiotherapy] for NSCLC," write the researchers in Journal of Thoracic Oncology .
However, they conclude that the continued validation of the PRS is required before it can be adapted for clinical use.
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