1. Cancer Registry and Statistics. Cancer information service, national cancer center, Japan, cancer mortality (1958‒2017). n.d. Available from: https://ganjoho.jp/en/professional/statistics/table_download.html. Accessed June 22, 2020.

2. The Japan Lung Cancer Society. Practice guidelines for lung cancer 2018, n.d. Available from: https://www.haigan.gr.jp/guideline/2018/1/2/180102010100.html. Accessed February 13, 2019.

3. Proton beam therapy

4. Proton Beam Therapy for Non-Small Cell Lung Cancer: Current Clinical Evidence and Future Directions