Clinical results of carbon ion radiotherapy for inoperable stage I non-small cell lung cancer: A Japanese national registry study (J-CROS-LUNG)
Nobuteru Kubo, Hiroaki Suefuji, Mio Nakajima, Sunao Tokumaru, Naoko Okano, Daisaku Yoshida, Osamu Suzuki, Hitoshi Ishikawa, Miyako Satouchi, Haruhiko Nakayama, Yoshiyuki Shioyama
Abstract
BACKGROUND AND PURPOSE: Radiotherapy is a standard treatment for inoperable stage I non-small cell lung cancer (NSCLC), and carbon-ion radiation therapy (CIRT) may be used for such treatment. Although CIRT for stage I NSCLC has demonstrated favorable outcomes in previous reports, the reports covered only single-institution studies. We conducted a prospective nationwide registry study including all CIRT institutions in Japan. MATERIALS AND METHODS: Ninety-five patients with inoperable stage I NSCLC were treated by CIRT between May 2016 and June 2018. The dose fractionations for CIRT were selected from several options approved by the Japanese Society for Radiation Oncology. RESULTS: The median patient age was 77 years. Comorbidity rates for chronic obstructive pulmonary disease and interstitial pneumonia were 43% and 26%, respectively. The most common schedule for CIRT was 60 Gy (relative biological effectiveness (RBE)) in four fractions, and the second most common was 50 Gy (RBE) in one fraction. The 3-year overall survival, cause-specific survival, and local control rates were 59.3%, 77.1%, and 87.3%, respectively. Female sex and ECOG performance status of 0-1 were favorable prognostic factors for overall survival in a multivariate analysis. No grade 4 or higher adverse event was observed. The 3-year cumulative incidence of grade 2 or higher radiation pneumonitis was 3.2%. The risk factors for grade 2 or higher radiation pneumonitis were a force expiratory volume in 1 second (FEV1) of <0.9 L and a total does of ≥ 67 Gy(RBE). CONCLUSION: This study provides real-world treatment outcomes of CIRT for inoperable. stage I NSCLC in Japan.