Multi-Institutional Retrospective Analysis of the Outcomes of Proton Beam Therapy for Patients With 1 to 3 Pulmonary Oligometastases From Various Primary Cancers

Norihiro Aibe; Hiroyuki Ogino; Satoshi Teramukai; Hideya Yamazaki; Hiromitsu Iwata; Yoshiro Matsuo; Tomoaki Okimoto; Masao Murakami; Motohisa Suzuki; Takeshi Arimura; Takashi Ogino; Shigeyuki Murayama; Hideyuki Harada; Masaki Nakamura; Tetsuo Akimoto; Hideyuki Sakurai

doi:10.1016/j.adro.2021.100690

Multi-Institutional Retrospective Analysis of the Outcomes of Proton Beam Therapy for Patients With 1 to 3 Pulmonary Oligometastases From Various Primary Cancers

Adv Radiat Oncol. 2021 Mar 26;6(4):100690. doi: 10.1016/j.adro.2021.100690. eCollection 2021 Jul-Aug.

Authors

Norihiro Aibe¹, Hiroyuki Ogino², Satoshi Teramukai³, Hideya Yamazaki¹, Hiromitsu Iwata², Yoshiro Matsuo⁴, Tomoaki Okimoto⁴, Masao Murakami⁵, Motohisa Suzuki⁵, Takeshi Arimura⁶, Takashi Ogino⁶, Shigeyuki Murayama⁷, Hideyuki Harada⁸, Masaki Nakamura⁹, Tetsuo Akimoto⁹, Hideyuki Sakurai¹⁰

Affiliations

¹ Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
² Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan.
³ Department of Biostatistics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
⁴ Department of Radiology, Hyogo Ion Beam Medical Center, Hyogo, Japan.
⁵ Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, Fukushima, Japan.
⁶ Medipolis Proton Therapy and Research Center, Ibusuki, Japan.
⁷ Division of Proton Therapy, Shizuoka Cancer Center, Shizuoka, Japan.
⁸ Division of Radiation Therapy, Shizuoka Cancer Center, Shizuoka, Japan.
⁹ Division of Radiation Oncology and Particle Therapy, National Cancer Center Hospital East, Kashiwa, Japan.
¹⁰ Department of Radiation Oncology, University of Tsukuba, Ibaraki, Japan.

Abstract

Purpose: Our purpose was to evaluate the efficacy of proton beam therapy (PBT) in patients with 1 to 3 pulmonary oligometastases from various primary cancers in Japan.

Methods and materials: This multi-institutional retrospective survey included 118 patients with 141 metastatic lung tumors from miscellaneous primary cancers, across 6 Japanese institutions, and involved the analyses of local progression-free rate (LPF), distant progression-free rate, progression-free survival rate, cause-specific survival rate, and overall survival rate (OS). Treatment-induced adverse effects of grade ≥2 were evaluated according to the Common Terminology Criteria for Adverse Events (version 4.0). Cox proportional hazards regression models were used in univariable analysis and multivariable analysis (MVA) for the identification of the prognostic factors of LPF and OS.

Results: The median follow-up duration from the time of PBT was 25.5 months. The major primary disease sites included colorectal cancer (42.4%), lung cancer (11.9%), head and neck cancer (8.5%), and kidney cancer (8.5%). For years 1, 2, and 3, LPFs were 92.2%, 86.3%, and 78.4%; distant progression-free rates were 59.1%, 44.1%, and 34.0%; progression-free survival rates were 49.6%, 31.7%, and 24.2%; cause-specific survival rates were 83.4%, 72.5%, and 64.8%; and OS rates were 79.0%, 67.8%, and 59.6%, respectively. Eight patients developed acute adverse effects (grade ≥2). Ten patients developed radiation pneumonitis (grade 2) as a late adverse effect. None of the patients developed severe late toxicity (grade ≥3). Colorectal cancer as the primary disease was the only prognostic factor associated with LPF that remained independently significant in the MVAs performed using 3 sets of parameters (hazard ratio [HR], 3.31-4.76 in 3 MVA sets). In the MVA, the significant prognostic factors for OS were performance status (HR, 2.78; 95% confidence interval, 1.01-7.67) and total tumor volume (HR, 1.01; 95% confidence interval, 1.00-1.02).

Conclusions: PBT provides promising outcomes for pulmonary oligometastasis with acceptable toxicities.