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The Predicted Radiation Response of Non-Small Cell Lung Cancer for SRS, SBRT and HDR Brachytherapy

Z Huang

Z Huang1*, Y Feng1 , S Lo2 , T Williams3 , J Grecula3 , N Mayr4 , W Yuh4 , (1) East Carolina University, Greenville, North Carolina, (2) Case Western Reserve University, Cleveland, OH, (3) Ohio State University, Columbus, OH, (4) University of Washington Medical Center, Seattle, WA


SU-F-T-105 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall

The data on the α/β ratio of non-small cell lung cancer (NSCLC) is scarce in the literature. We have previously proposed a generalized LQ (gLQ) model to address the high dose dilemma of the LQ model. In this study, we applied the gLQ model to both the patients and in vitro cell irradiation data treated with a large range of doses, and investigated the α/β ratio in NSCLC.

150 patients with T1T2 and non-T1T2 stages were treated with stereotactic body radiotherapy (SBRT). In vitro datasets of 14 NSCLC cell lines from the National Cancer Institute published in Eur J Cancer Clin Oncol. 25(3):527-534 (1989) and 7 NSCLC cell lines published in Cancer Res 57:4285–300 (1997) were included. The gLQ model was used to fit datasets. The least χ2 method was adopted to determine the goodness of fit. Errors of the model parameters were determined by propagating minimal χ2. The α/β ratios from both the patients and these in vitro NSCLC cell lines were obtained.

The average of α/β ratios for T1T2 and non-T1T2 NSCLC was 1.45 Gy. The same type of cell lines irradiated with different modalities but almost the same dose rate yielded approximately the same α/β ratio. The average of α/β ratios for NSCLC cell lines in this study was 5.45 Gy.

The difference in the α/β ratios between the patients and in vitro cell data is expected and the lower α/β ratio for patients suggests the higher radiosensitivity, which could be associated with higher tumor perfusion or other tumor microenvironmental effects. The α/β ratios derived from the gLQ model can be used in high dose regions or high fraction sizes and are useful to extend our clinical experience accumulated from conversional low-dose fractionation to high dose irradiation schedules.

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