Dosimetric Predictors for Acute Esophagitis During Radiation Therapy for Lung Cancer - Results of a Large Statewide Observational Study

Publication date: Available online 19 July 2017
Source:Practical Radiation Oncology
Author(s): Peter Paximadis, Matthew Schipper, Martha Matuszak, Mary Feng, Shruti Jolly, Thomas Boike, Inga Grills, Larry Kestin, Benjamin Movsas, Kent Griffith, Gregory Gustafson, Jean Moran, Teamour Nurushev, Jeffrey Radawski, Lori Pierce, James Hayman
PurposeThe purpose of this study is to identify dosimetric variables that best predict for acute esophagitis in patients treated for locally advanced non-small cell lung cancer in a prospectively accrued state-wide consortium.Methods and MaterialsPatients receiving definitive radiation therapy for stage II-III NSCLC within the Michigan Radiation Oncology Quality Consortium (MROQC) were included in the analysis. DVH data were analyzed to determine dose metrics (V10, V20, V30, V40, V50, and V60), as well as maximum dose to 2cc (D2cc), mean dose (MD), and generalized equivalent uniform dose (gEUD). Logistic regression models were used to characterize the risk of toxicity as a function of dose and other covariates. The ability of each variable to predict esophagitis, individually or in a multivariate model, was quantified by ROC analysis.ResultsThere were 533 patients who met study criteria and were included; 437 (81.9%) developed any grade of esophagitis. Significant variables on univariate analysis for grade? 2 esophagitis were concurrent chemotherapy, V20, V30, V40, V50, V60, MD, D2cc, and gEUD. For grade? 3 esophagitis, the predictive variables were: V30, V40, V50, V60, MD, D2cc, and gEUD. In multivariable modeling, gEUD was the most significant predictor of both grade? 2 and grade? 3 esophagitis. When gEUD was excluded from the model, D2cc was selected as the most predictive variable for grade? 3 esophagitis. For an estimated risk of grade? 3 esophagitis of 5%, the threshold values for gEUD and D2cc were 59.3Gy and 68Gy, respectively.ConclusionsIn this study, we report the novel finding that generalized equivalent uniform dose and D2cc, rather than mean dose, were the most predictive dose metrics for severe esophagitis. To limit the estimated risk of grade? 3 esophagitis to <5%, thresholds of 59.3Gy and 68Gy were identified for gEUD and D2cc, respectively.



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