Dosemetric parameters predictive of rib fractures after proton beam therapy for early-stage lung cancer

Yojiro Ishikawa, Tatsuya Nakamura, Takahiro Kato, Noriyuki Kadoya, Motohisa Suzuki, Yusuke Azami, Masato Hareyama, Yasuhiro Kikuchi, Keiichi Jingu

Research output: Contribution to journalArticle

3 Citations (Scopus)

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 Gy3 (relative biological effectiveness (RBE)) was more than 3.7 cm3 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 Gy3 (RBE) was the most significant parameter for predicting RFs.

Original languageEnglish
Pages (from-to)339-345
Number of pages7
JournalTohoku Journal of Experimental Medicine
Volume238
Issue number4
DOIs
Publication statusPublished - 2016 Jan 1

Keywords

  • Bragg peak
  • Early-stage lung cancer
  • Proton beam therapy
  • Rib fracture
  • Stereotactic radiotherapy

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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