Niraj Mehta1, Christopher R King1, Nzhde Agazaryan1, Michael Steinberg1, Amanda Hua1, Percy Lee2. 1. Department of Radiation Oncology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California. 2. Department of Radiation Oncology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California. Electronic address: percylee@mednet.ucla.edu.
Abstract
PURPOSE: To determine the relationship between tumor control probability (TCP) and biological effective dose (BED) for radiation therapy in medically inoperable stage I non-small cell lung cancer (NSCLC). METHODS AND MATERIALS: Forty-two studies on 3-dimensional conformal radiation therapy (3D-CRT) and SBRT for stage I NSCLC were reviewed for tumor control (TC), defined as crude local control ≥ 2 years, as a function of BED. For each dose-fractionation schedule, BED was calculated at isocenter using the linear quadratic (LQ) and universal survival curve (USC) models. A scatter plot of TC versus BED was generated and fitted to the standard TCP equation for both models. RESULTS: A total of 2696 patients were included in this study (SBRT: 1640; 3D-CRT: 1056). Daily fraction size was 1.2-4 Gy (total dose: 48-102.9) with 3D-CRT and 6-26 (total dose: 20-66) with SBRT. Median BED was 118.6 Gy (range, 68.5-320.3) and 95.6 Gy (range, 46.1-178.1) for the LQ and USC models, respectively. According to the LQ model, BED to achieve 50% TC (TCD50) was 61 Gy (95% confidence interval, 50.2-71.1). TCP as a function of BED was sigmoidal, with TCP ≥ 90% achieved with BED ≥ 159 Gy and 124 Gy for the LQ and USC models, respectively. CONCLUSIONS: Dose-escalation beyond a BED 159 by LQ model likely translates into clinically insignificant gain in TCP but may result in clinically significant toxicity. When delivered with SBRT, BED of 159 Gy corresponds to a total dose of 53 Gy in 3 fractions at the isocenter.
PURPOSE: To determine the relationship between tumor control probability (TCP) and biological effective dose (BED) for radiation therapy in medically inoperable stage I non-small cell lung cancer (NSCLC). METHODS AND MATERIALS: Forty-two studies on 3-dimensional conformal radiation therapy (3D-CRT) and SBRT for stage I NSCLC were reviewed for tumor control (TC), defined as crude local control ≥ 2 years, as a function of BED. For each dose-fractionation schedule, BED was calculated at isocenter using the linear quadratic (LQ) and universal survival curve (USC) models. A scatter plot of TC versus BED was generated and fitted to the standard TCP equation for both models. RESULTS: A total of 2696 patients were included in this study (SBRT: 1640; 3D-CRT: 1056). Daily fraction size was 1.2-4 Gy (total dose: 48-102.9) with 3D-CRT and 6-26 (total dose: 20-66) with SBRT. Median BED was 118.6 Gy (range, 68.5-320.3) and 95.6 Gy (range, 46.1-178.1) for the LQ and USC models, respectively. According to the LQ model, BED to achieve 50% TC (TCD50) was 61 Gy (95% confidence interval, 50.2-71.1). TCP as a function of BED was sigmoidal, with TCP ≥ 90% achieved with BED ≥ 159 Gy and 124 Gy for the LQ and USC models, respectively. CONCLUSIONS: Dose-escalation beyond a BED 159 by LQ model likely translates into clinically insignificant gain in TCP but may result in clinically significant toxicity. When delivered with SBRT, BED of 159 Gy corresponds to a total dose of 53 Gy in 3 fractions at the isocenter.
Authors: Feng Liu; An Tai; Percy Lee; Tithi Biswas; George X Ding; Isaam El Naqa; Jimm Grimm; Andrew Jackson; Feng-Ming Spring Kong; Tamara LaCouture; Billy Loo; Moyed Miften; Timothy Solberg; X Allen Li Journal: Radiother Oncol Date: 2016-11-18 Impact factor: 6.280
Authors: Jeho Jeong; Jung Hun Oh; Jan-Jakob Sonke; Jose Belderbos; Jeffrey D Bradley; Andrew N Fontanella; Shyam S Rao; Joseph O Deasy Journal: Clin Cancer Res Date: 2017-05-24 Impact factor: 12.531