SBRT of lung cancerDouble-scattered proton-based stereotactic body radiotherapy for stage I lung cancer: A dosimetric comparison with photon-based stereotactic body radiotherapy
Section snippets
Materials and methods
Beginning in November 2005, patients at the University of Florida (UF) with early-stage NSCLC were treated on an Institutional Review Board-approved protocol with xSBRT to a total dose of 48 Gy delivered in 4 fractions of 12 Gy. Eight patients on this study with peripherally located stage I NSCLC were identified for retrospective treatment planning with pSBRT, including 3 patients with T1N0Mx (maximum tumor diameters, 1.9 cm, 2.1 cm, and 2.4 cm) and 5 patients with T2N0Mx (maximum tumor diameters,
Results
Table 1 describes the target volumes and coverage for the eight cases. The median PTV treated was 77 cm3 (range, 38–138 cm3) and the CTV was 47 cm3 (range, 20–92 cm3). As expected, CTV coverage was comparable (median CTV D99% = 48.6 Gy vs 48 CGE with xSBRT and pSBRT, respectively), while PTV coverage was marginally worse with pSBRT (median PTV D95% = 48 Gy vs 46.5 CGE with xSBRT and pSBRT, respectively). Table 2 shows the dosimetric end points for the specified critical organs at risk for the xSBRT plans
Discussion
Surgery has been the “gold standard” of treatment for patients with early-stage NSCLC. SBRT, however, offers medically inoperable patients with early-stage NSCLC a less invasive treatment approach with local-control rates comparable to those observed with surgical resection [23]. Because the efficacy of SBRT appears to be comparable to surgery, even medically operable patients are considering SBRT in lieu of lobectomy and this approach is currently being tested by the RTOG.
Although significant
Conclusion
Based on our SBRT treatment approach, we found that 3D-CPT significantly reduced the radiation dose to the ipsilateral lung, total lung, heart, esophagus, trachea, and ipsilateral bronchus. This reduction may translate into a clinically important reduction in side effects from SBRT and is the rationale for our present phase I/II study of using 3D-CPT for patients with early-stage NSCLC.
Conflicts of interest statement
The authors have no conflicts of interests to declare.
Role of the funding source
The authors have no source of funding to declare.
Acknowledgements
The authors would like to thank the editorial staff at the University of Florida, Department of Radiation Oncology for helping to edit and prepare the manuscript.
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