Establishing the feasibility of the dosimetric compliance criteria of RTOG 1308: phase III randomized trial comparing overall survival after photon versus proton radiochemotherapy for inoperable stage II-IIIB NSCLC.

Tawfik Giaddui,Jennifer Presley,Ying Xiao,Q Jackie Wu,Radhe Mohan,Jaques B Bluett,Elizabeth O’Meara,Jeffrey D Bradley,Liyong Lin,James Galvin,Wenzhou Chen,Michael Gillin,Jialu Yu,Xiaodong Zhang,Kevin Moore,Zhongxing Liao,Yutao U T Gong,Lulin Yuan,Charles B Simone

doi:10.1186/s13014-016-0640-8

Abstract

BackgroundTo establish the feasibility of the dosimetric compliance criteria of the RTOG 1308 trial through testing against Intensity Modulation Radiation Therapy (IMRT) and Passive Scattering Proton Therapy (PSPT) plans.MethodsTwenty-six lung IMRT and 26 proton PSPT plans were included in the study. Dose Volume Histograms (DVHs) for targets and normal structures were analyzed. The quality of IMRT plans was assessed using a knowledge-based engineering tool.ResultsMost of the RTOG 1308 dosimetric criteria were achieved. The deviation unacceptable rates were less than 10 % for most criteria; however, a deviation unacceptable rate of more than 20 % was computed for the planning target volume minimum dose compliance criterion. Dose parameters for the target volume were very close for the IMRT and PSPT plans. However, the PSPT plans led to lower dose values for normal structures. The dose parameters in which PSPT plans resulted in lower values than IMRT plans were: lung V5Gy (%) (34.4 in PSPT and 47.2 in IMRT); maximum spinal cord dose (31.7 Gy in PSPT and 43.5 Gy in IMRT); heart V5Gy (%) (19 in PSPT and 47 in IMRT); heart V30Gy (%) (11 in PSPT and 19 in IMRT); heart V45Gy (%) (7.8 in PSPT and 12.1 in IMRT); heart V50% (Gy) (7.1 in PSPT and 9.8 in IMRT) and mean heart dose (7.7 Gy in PSPT and 14.9 Gy in IMRT).ConclusionsThe revised RTOG 1308 dosimetric compliance criteria are feasible and achievable.

Highlights

Lung cancer is the main cause of cancer death in the United States (US) [1, 2]
Proton therapy generally allows for reduced doses to organs at risk compared with photon therapy due to the physical properties of the proton beam, with essentially no dose delivered distal to the characteristic Bragg Peak [4, 5]
We assessed the feasibility of the new and more stringent dosimetric criteria of the RTOG 1308 trial using the Intensity Modulation Radiation Therapy (IMRT) and Passive Scattering Proton Therapy (PSPT) plans submitted during the design stage of the trial

Summary

Introduction

Lung cancer is the main cause of cancer death in the United States (US) [1, 2]. In the year 2015, a total of 221,200 new cases and 158,040 deaths from lung cancer are estimated in the US [3]. RTOG 1308 is a phase III randomized trial comparing overall survival after photon versus proton chemoradiotherapy for inoperable stage II-IIIB NSCLC. The trial’s purpose is to determine if proton therapy can improve overall survival over IMRT by reducing the risk of severe toxicity to organs at risk as compared to photon therapy, and new and more stringent dose constraints were employed [2]. We assessed the feasibility of the new and more stringent dosimetric criteria of the RTOG 1308 trial using the IMRT and PSPT plans submitted during the design stage of the trial. To establish the feasibility of the dosimetric compliance criteria of the RTOG 1308 trial through testing against Intensity Modulation Radiation Therapy (IMRT) and Passive Scattering Proton Therapy (PSPT) plans

Objectives

Methods

Results