Clinical characteristics of organizing pneumonia following stereotactic body radiation therapy for lung malignancies

• Main Authors: Masayuki Ito, Hitoshi Takagi, Fumitaka Ito, Hidetoshi Kobayashi, Shinya Hayashi, Hiroshi Toyama
• Format: Article
• Language: English
• Published: Fujita Medical Society 2017-02-01
• Series: Fujita Medical Journal
• Subjects: radiation pneumonitis; organizing pneumonia; stereotactic body radiation therapy
• Online Access: https://www.jstage.jst.go.jp/article/fmj/3/1/3_12/_pdf/-char/en
• ISSN: 2189-7247; 2189-7255

Objective: Radiation pneumonitis and organizing pneumonia (OP) are the two primary forms of lung damage that can occur following lung irradiation. The goal of this study was to clarify the clinical characteristics of OP after stereotactic body radiation therapy (SBRT) for lung malignancies. Methods: This study included 75 patients with lung malignancies who underwent SBRT from April 2013 to January 2015. The diagnosis of OP was based on lung computed tomography findings and previously established criteria. Results: OP was observed in 6 of 75 patients (8%) and occurred in regions with a steep dose gradient ranging from 30% to 90%. The time to OP occurrence ranged from 1 to 4 months after completion of SBRT (mean, 84 days). No patients had symptoms suggestive of pneumonia, such as a fever or cough, at the time of computed tomography. Conclusion: OP developed in regions with a steep dose gradient. This mechanism explains why the incidence of OP after SBRT was higher than that after postoperative radiation for breast cancer and non-SBRT irradiation for lung cancer.