Patterns and correlates of treatment failure in relation to isodose distribution in non-small cell lung cancer: An analysis of 1522 patients in the modern era

Publication date: Available online 17 October 2017
Source:Radiotherapy and Oncology
Author(s): Todd A. Pezzi, Chad Tang, Cameron W. Swanick, Penny Fang, Kenneth Hess, Ting Xu, Stephen M. Hahn, Joe Y. Chang, Zhongxing Liao, Daniel Gomez
Background and purposeTo examine the relationship between radiation dose and tumor control in limited stage non-small cell lung cancer (NSCLC).Materials and methodsWe searched a database of 1552 patients who received radiation therapy for non-metastatic NSCLC between 2000 and 2016. The primary endpoint was freedom from in-field failure.ResultsIncreasing BED correlated with decreasing estimated gross tumor volume–planning target volume expansion, and on multivariable analysis increasing BED was associated with an increased chance of field-edge failures (hazard ratio [HR] 1.032, 95% confidence interval [CI] 1.004–1.062, P = 0.027). Increasing BED also correlated with improved freedom from in-field failure on multivariable analysis (HR 0.978, 95% CI 0.964–0.993, P = 0.003), with the dose–response curve showing a sigmoidal relationship between increasing BED and freedom from in-field failure.ConclusionIn this large study of patients treated in the modern era with varying dose fractionation regimens, higher BED was associated with improved freedom from in-field failure, and that this relationship appeared to be consistent with the classically described sigmoid shape. We also found that increased BED was associated with higher field-edge failures, implying that margin size may need to be further studied in patients receiving ablative regimens of radiation.



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