Proton Radiation Therapy Offers Reduced Normal Lung and Bone Marrow Exposure for Patients Receiving Dose-Escalated Radiation Therapy for Unresectable Stage III Non-Small- Cell Lung Cancer: A Dosimetric Study R. Charles Nichols, 1 Soon N. Huh, 1 Randal H. Henderson, 1 Nancy P. Mendenhall, 1 Stella Flampouri, 1 Zuofeng Li, 1 Harry J. D’Agostino, 2 J. Davis Cury, 3 Dat C. Pham, 4 Bradford S. Hoppe 1 Abstract Introduction: The purpose of this study was to determine the potential benefit of proton radiation therapy over photon radiation therapy in patients with unresectable stage III non-small-cell lung cancer. Materials and Methods: Optimized 3-dimensional conformal photon (3DCRT), intensity-modulated radiation therapy (IMRT) and proton therapy (PT) plans were generated for 8 consecutive patients with unresectable stage III non–small-cell lung cancer using the same target goals and normal tissue constraints. The radiation exposure to non-targeted normal structures, including lung, bone marrow, esophagus, heart, and spinal cord, were compared. Photon doses are expressed in gray (Gy). Proton doses are expressed in cobalt gray equivalents (CGE). Results: In all patients, 3DCRT, IMRT, and PT plans, achieved the dose goals for the target volumes. Compared with the 3DCRT plans, proton plans offered a median 29% reduction in normal lung V 20 Gy (CGE), a median 33% reduction in mean lung dose (MLD), and a median 30% reduction in the volume of bone marrow receiving a dose of 10 Gy (CGE). Compared with the IMRT plans, the proton plans offered a median 26% reduction in normal lung V 20 Gy (CGE), a median 31% reduction in MLD, and a median 27% reduction in the volume of bone marrow receiving a dose of 10 Gy (CGE). Conclusion: By reducing the volumes of normal structures irradiated, protons can potentially improve the therapeutic index for patients with unresectable stage III non-small-cell lung cancer receiving combined radiation therapy and chemotherapy. Clinical Lung Cancer, Vol. 12, No. 4, 252-7 © 2011 Published by Elsevier Inc. Keywords: Bone marrow exposure, Chemotherapy, Normal lung exposure, Proton therapy, Radiotherapy Introduction Favorable-performance patients with regionally advanced stage III non–small-cell lung cancer (NSCLC) are conventionally treated with concurrent chemotherapy and radiation therapy. To achieve cure, radiation therapy and chemotherapy must be each be given in sufficient doses to sterilize the gross intrathoracic disease and eradi- cate distant micrometastases. Four- to 5-year survival rates for con- temporary prospective series of selected favorable-performance pa- tients range from 16% to 21%. 1-3 These same series show intrathoracic failure rates ranging from 31% 3 to 50% 1 and distant Presented in part at the LALCa 2008 - 3rd Latin American Conference on Lung Cancer – Tercera Conferencia Latinoamericana sobre Cancer Pulmonar-Vina del Mar, Chile-October 9-10, 2008 1 University of Florida Proton Therapy Institute, University of Florida College of Medicine, Jacksonville, FL 2 Department of Surgery, University of Florida College of Medicine, Jacksonville, FL 3 Division of Pulmonary Medicine, University of Florida College of Medicine, Jacksonville, FL 4 Division of Medical Oncology, University of Florida College of Medicine, Jacksonville, FL Submitted: Oct 1, 2010; Revised: Jan 18, 2011; Accepted: Jan 24, 2011 Address for correspondence: Romaine C. Nichols, Jr, MD, University of Florida Proton Therapy Institute, 2015 North Jefferson Street, Jacksonville, FL Fax: 904-588-1300; e-mail contact: rnichols@floridaproton.org Original Study 252 Clinical Lung Cancer July 2011 1525-7304/$ - see frontmatter © 2011 Published by Elsevier Inc. doi: 10.1016/j.cllc.2011.03.027