Stereotactic body radiation therapy and 3-dimensional conformal radiotherapy for stage I non-small cell lung cancer: A pooled analysis of biological equivalent dose and local control

Niraj Mehta; Christopher R King; Nzhde Agazaryan; Michael Steinberg; Amanda Hua; Percy Lee

doi:10.1016/j.prro.2011.10.004

Stereotactic body radiation therapy and 3-dimensional conformal radiotherapy for stage I non-small cell lung cancer: A pooled analysis of biological equivalent dose and local control

Pract Radiat Oncol. 2012 Oct-Dec;2(4):288-295. doi: 10.1016/j.prro.2011.10.004. Epub 2011 Dec 3.

Authors

Niraj Mehta¹, Christopher R King¹, Nzhde Agazaryan¹, Michael Steinberg¹, Amanda Hua¹, Percy Lee²

Affiliations

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.

PMID: 24674167
DOI: 10.1016/j.prro.2011.10.004

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.