Dosemetric Parameters Predictive of Rib Fractures after Proton Beam Therapy for Early-Stage Lung Cancer

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Author(s)

    • Ishikawa Yojiro
    • Department of Radiation Oncology, Tohoku University Graduate School of Medicine
    • Nakamura Tatsuya
    • Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, Southern Tohoku Research Institute for Neuroscience
    • Kato Takahiro
    • Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, Southern Tohoku Research Institute for Neuroscience
    • Kadoya Noriyuki
    • Department of Radiation Oncology, Tohoku University Graduate School of Medicine
    • Suzuki Motohisa
    • Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, Southern Tohoku Research Institute for Neuroscience
    • Azami Yusuke
    • Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, Southern Tohoku Research Institute for Neuroscience
    • Hareyama Masato
    • Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, Southern Tohoku Research Institute for Neuroscience
    • Kikuchi Yasuhiro
    • Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, Southern Tohoku Research Institute for Neuroscience
    • Jingu Keiichi
    • Department of Radiation Oncology, Tohoku University Graduate School of Medicine

Abstract

Proton beam therapy (PBT) is the preferred modality for early-stage lung cancer. Compared with X-ray therapy, PBT offers good dose concentration as revealed by the characteristics of the Bragg peak. Rib fractures (RFs) after PBT lead to decreased quality of life for patients. However, the incidence of and the risk factors for RFs after PBT have not yet been clarified. We therefore explored the relationship between irradiated rib volume and RFs after PBT for early-stage lung cancer. The purpose of this study was to investigate the incidence and the risk factors for RFs following PBT for early-stage lung cancer. We investigated 52 early-stage lung cancer patients and analyzed a total of 215 irradiated ribs after PBT. Grade 2 RFs occurred in 12 patients (20 ribs); these RFs were symptomatic without displacement. No patient experienced more severe RFs. The median time to grade 2 RFs development was 17 months (range: 9-29 months). The three-year incidence of grade 2 RFs was 30.2%. According to the analysis comparing radiation dose and rib volume using receiver operating characteristic curves, we demonstrated that the volume of ribs receiving more than 120 Gy<sub>3</sub> (relative biological effectiveness (RBE)) was more than 3.7 cm<sup>3</sup> at an area under the curve of 0.81, which increased the incidence of RFs after PBT (P < 0.001). In this study, RFs were frequently observed following PBT for early-stage lung cancer. We demonstrated that the volume of ribs receiving more than 120 Gy<sub>3</sub> (RBE) was the most significant parameter for predicting RFs.

Journal

  • The Tohoku Journal of Experimental Medicine

    The Tohoku Journal of Experimental Medicine 238(4), 339-345, 2016

    Tohoku University Medical Press

Codes

  • NII Article ID (NAID)
    130005145015
  • Text Lang
    ENG
  • ISSN
    0040-8727
  • Data Source
    J-STAGE 
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