Prognostic analysis of radiation pneumonitis: carbon-ion radiotherapy in patients with locally advanced lung cancer

Kazuhiko Hayashi,Tadashi Kamada,Kazuhiko Ogawa,Naoyoshi Yamamoto,Masataka Karube,Mio Nakajima,Naruhiro Matsufuji,Hiroshi Tsuji

doi:10.1186/s13014-017-0830-z

Abstract

BackgroundCarbon-ion radiotherapy (CIRT) is a promising treatment for locally advanced non-small-cell lung cancer, especially for patients with inoperable lung cancer. Although the incidence of CIRT-induced radiation pneumonitis (RP) ≥ grade 2 ranges from 2.5 to 9.9%, the association between CIRT-induced RP and dosimetric parameters is not clear. Herein, we identified prognostic factors associated with symptomatic RP after CIRT for patients with non-small-cell lung cancer.MethodsClinical results of 65 patients treated with CIRT between 2000 and 2015 at the National Institute of Radiological Sciences were retrospectively analyzed. Clinical stage II B disease (TNM classification) was the most common stage among the patients (45%). The median radiation dose was 72 Gy (68–76) relative biological effectiveness (RBE) in 16 fractions. In cases involving metastatic lymph nodes, prophylactic irradiation of mediastinal lymph nodes was performed at a median dose of 49.5 Gy (RBE). The median follow-up was 22 months.ResultsGrade 2 and grade 3 RP occurred in 6 and 3 patients (9 and 5%), respectively. No patients developed grade 4 or 5 RP. Using univariate analysis, vital capacity as a percentage of predicted (%VC), forced expiratory volume in 1 s (FEV1), mean lung dose (MLD), volume of lung receiving ≥5 Gy (RBE) (V5), V10, V20 and V30 were determined to be the significant predictive factors for ≥ grade 2 RP. The receiver operating characteristic (ROC) analysis revealed the cutoff values for %VC, FEV1, MLD, V5, V10, V20 and V30 for ≥ grade 2 RP, which were 86.9%, 1.16 L, 12.5 Gy (RBE), 28.8, 29.9, 20.1 and 15.0%, respectively. In addition, the multivariate analysis revealed that %VC <86.9% (odds ratio = 13.7; p = 0.0041) and V30 ≥ 15% (odds ratio = 6.1; p = 0.0221) were significant risk factors.ConclusionsOur study demonstrated the risk factors for ≥ grade 2 RP after carbon-ion radiotherapy for patients with locally advanced lung cancer.

Highlights

Primary lung cancer is one of the most common cancers worldwide, and the most frequent type is non-small-cell lung cancer
The multivariate analysis revealed that %Percent of vital capacity (VC)
Our study demonstrated the risk factors for ≥ grade 2 radiation pneumonitis (RP) after carbon-ion radiotherapy for patients with locally advanced lung cancer

Summary

Introduction

Primary lung cancer is one of the most common cancers worldwide, and the most frequent type is non-small-cell lung cancer. Patients with locally advanced non-smallcell lung cancer undergo surgery, chemotherapy, and/or radiotherapy. Hayashi et al Radiation Oncology (2017) 12:91 in lung cancer patients, the incidence of symptomatic RP has ranged from 17 to 37% [3,4,5,6,7], and the incidence of CIRT-induced RP ≥ grade 2 has ranged from 2.5 to 9.9% [8, 9]. Carbon-ion radiotherapy (CIRT) is a promising treatment for locally advanced non-small-cell lung cancer, especially for patients with inoperable lung cancer. The incidence of CIRT-induced radiation pneumonitis (RP) ≥ grade 2 ranges from 2.5 to 9.9%, the association between CIRT-induced RP and dosimetric parameters is not clear. We identified prognostic factors associated with symptomatic RP after CIRT for patients with non-small-cell lung cancer

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Results

Discussion

Conclusion