Risk of radiation-induced pneumonitis after helical and static-port tomotherapy in lung cancer patients and experimental rats.

Xianglan Zhang,Ik Jae Lee,Zhenlong Zheng,Lianhua Zhu,You Keun Shin

doi:10.1186/s13014-015-0502-9

Abstract

BackgroundRadiotherapy (RT) is one of the major non-operative treatment modalities for treating lung cancer. Tomotherapy is an advanced type of intensity-modulated radiotherapy (IMRT) in which radiation may be delivered in a helical fashion. However, unexpected pneumonitis may occur in patients treated with tomotherapy, especially in combination with chemotherapy, as a result of extensive low-dose radiation of large lung volumes. The aim of our study was to investigate the risk of radiation-induced pneumonitis after helical-mode and static-mode tomotherapy in patients with lung cancer and in an animal model.MethodA total of 63 patients with primary lung cancer who were treated with static or helical tomotherapy with or without concurrent chemoradiotherapy (CCRT) were analyzed. Additionally, rats with radiation-induced pulmonary toxicity, which was induced by the application of helical or static tomography with or without CCRT, were evaluated.ResultsHelical-mode tomotherapy resulted in a significantly higher rate of late radiation pneumonitis in lung cancer patients than static-mode tomotherapy when evaluated by the Radiation Therapy Oncology Group (RTOG) and National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) scoring system. In the animal model, helical tomotherapy alone induced significantly higher expression of interleukin (IL)-1α, IL-1β, IL-6, and transforming growth factor (TGF)-β in lung specimens, especially on the untreated side, compared to static tomotherapy alone. Additionally, rats treated with helical tomotherapy and CCRT demonstrated significantly higher expression of inflammatory cytokines compared to those treated with static tomotherapy and CCRT.ConclusionRat models treated with tomotherapy with or without CCRT could present similar patterns of pulmonary toxicity to those shown in lung cancer patients. The models can be used in further investigations of radiation induced pulmonary toxicity.

Highlights

Radiotherapy (RT) is one of the major non-operative treatment modalities for treating lung cancer
Helical-mode tomotherapy resulted in a significantly higher rate of late radiation pneumonitis in lung cancer patients than static-mode tomotherapy when evaluated by the Radiation Therapy Oncology Group (RTOG) and National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) scoring system
Rat models treated with tomotherapy with or without concurrent chemoradiotherapy (CCRT) could present similar patterns of pulmonary toxicity to those shown in lung cancer patients

Summary

Introduction

Radiotherapy (RT) is one of the major non-operative treatment modalities for treating lung cancer. Unexpected pneumonitis may occur in patients treated with tomotherapy, especially in combination with chemotherapy, as a result of extensive low-dose radiation of large lung volumes. The aim of our study was to investigate the risk of radiation-induced pneumonitis after helical-mode and static-mode tomotherapy in patients with lung cancer and in an animal model. Ongoing investigations have improved the survival of cancer patients and minimized RT-related toxicities through the design of new RT modalities, including 3-dimensional conformal RT based on computed radiography imaging, Tomotherapy (Accuray, Palo Alto, USA) is a form of IMRT which is integrated with an image guidance system, and helical tomotherapy delivers IMRT in a continuous helix for improved dose conformity to malignant tissues [3, 4]. Unexpected pneumonitis may occur in patients treated with helical tomotherapy, especially in combination with chemotherapy, as a result of extensive low-dose radiation of large lung volumes [9, 10]

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