{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,26]],"date-time":"2026-05-26T10:06:45Z","timestamp":1779790005491,"version":"3.53.1"},"reference-count":28,"publisher":"Oxford University Press (OUP)","issue":"3","license":[{"start":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T00:00:00Z","timestamp":1776643200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,5,26]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>This study aimed to investigate the role of proton beam therapy (PT) in patients with unresectable distal cholangiocarcinoma (dCCA), with a special focus on elderly patients. We analyzed data from an updated multi-institutional prospective registry that included all Japanese proton beam facilities. The endpoints were local control (LC), progression-free survival (PFS), overall survival (OS) and toxicity. We included 36 patients with unresectable dCCA who were treated with PT at a median prescribed dose of 60\u00a0Gy (RBE) in 30 fractions. With a median follow-up of 12.4\u00a0months, the median survival time was 18.9\u00a0months, and the 1-year OS were 68.8%. The 1-year LC and PFS rates were 80.6 and 42.7%, respectively. The 1-year OS, LC and PFS rates for elderly patients (aged \u226580\u00a0years) were 65.6, 82.3 and 40.9%, respectively, showing no significant difference compared to younger patients (OS: 74.1%, P\u2009=\u20090.853; LC: 78.7%, P\u2009=\u20090.708; PFS: 45.5%, P\u2009=\u20090.654). However, four patients (11.1%) experienced grade \u22653 PT-related adverse reactions, exclusively among elderly patients (4\/24\u2009=\u200916.6% vs. 0\/12\u2009=\u20090% in younger patients, P\u2009=\u20090.278). These reactions were significantly higher with prescribed doses of equivalent 2-Gy fractions (EQD2)&amp;gt;60\u00a0Gy (3\/6\u2009=\u200950%) than with EQD2\u2009\u2264\u200960\u00a0Gy (1\/30\u2009=\u20093.3%, P\u2009=\u20090.0104). PT showed good efficacy and acceptable toxicity for unresectable dCCA, even in patients aged \u226580\u00a0years, who showed outcomes similar to those of their younger counterparts. However, for elderly patients, a higher prescribed dose of EQD2 \u226560\u00a0Gy should be used with caution.<\/jats:p>","DOI":"10.1093\/jrr\/rrag018","type":"journal-article","created":{"date-parts":[[2026,2,25]],"date-time":"2026-02-25T12:45:01Z","timestamp":1772023501000},"page":"412-419","source":"Crossref","is-referenced-by-count":0,"title":["Proton beam therapy for patients with distal cholangiocarcinoma: a multicenter prospective registry study (Influence of age factor)"],"prefix":"10.1093","volume":"67","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7508-7217","authenticated-orcid":false,"given":"Hideya","family":"Yamazaki","sequence":"first","affiliation":[{"name":"Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine , 465 Kajiicho Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kei","family":"Shibuya","sequence":"additional","affiliation":[{"name":"Gunma University Heavy Ion Medical Center , 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takuya","family":"Kimoto","sequence":"additional","affiliation":[{"name":"Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine , 465 Kajiicho Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7083-5877","authenticated-orcid":false,"given":"Motohisa","family":"Suzuki","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Southern TOHOKU Proton Therapy Center , 172 Yatsuyamada, Koriyama City, Fukushima Prefecture 963-8052 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9530-0337","authenticated-orcid":false,"given":"Masao","family":"Murakami","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Southern TOHOKU Proton Therapy Center , 172 Yatsuyamada, Koriyama City, Fukushima Prefecture 963-8052 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-1198-5554","authenticated-orcid":false,"given":"Kazuki","family":"Terashima","sequence":"additional","affiliation":[{"name":"Department of Radiology, Hyogo Ion Beam Medical Center , 1-2-1 Koto, Shingu-cho, Tatsuno City, Hyogo 679-5165 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6632-4356","authenticated-orcid":false,"given":"Takashi","family":"Iizumi","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Proton Medical Research Center, University of Tsukuba Hospital , 2-1-1, Amakubo, Tsukuba, 305-8576 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3017-2017","authenticated-orcid":false,"given":"Masaru","family":"Wakatsuki","sequence":"additional","affiliation":[{"name":"QST Hospital, National Institutes for Quantum Science and Technology , 4-9-1 Anagawa, chiba-shi, Chiba 263-8555 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takashi","family":"Ogino","sequence":"additional","affiliation":[{"name":"Medipolis Proton Therapy and Research Center, Medipolis Medical Research Institute , 4423, Higashikata, Ibusuki, Kagoshima, 891-0304 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masaru","family":"Takagi","sequence":"additional","affiliation":[{"name":"Proton Therapy Center, Sapporo Teishinkai Hospital , 1-3-1, Kita 33-jo Higashi, Higashi-ku, Sapporo, Hokkaido, 065-0033 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masayuki","family":"Araya","sequence":"additional","affiliation":[{"name":"Proton Therapy Center, Aizawa Hospital , 2-5-1 Honjou Matsumoto-City, Nagano, 390-8510 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sae","family":"Matsumoto","sequence":"additional","affiliation":[{"name":"Proton Therapy Center, Fukui Prefectural Hospital , 2-8-1 Yotsui, Fukui City, Fukui Prefecture, 910-8526 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6035-7402","authenticated-orcid":false,"given":"Hiroyuki","family":"Ogino","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City University West Medical Center , 1-1-1, Nagoya ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5276-3665","authenticated-orcid":false,"given":"Takayuki","family":"Hashimoto","sequence":"additional","affiliation":[{"name":"Global Center for Biomedical Science and Engineering, Faculty of Medicine, Hokkaido University , 5-chome, Kita 14-jo Nishi, Kita-ku, Sapporo, Hokkaido, 060-8648 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hidehiro","family":"Hojo","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology and Particle Therapy, National Cancer Center Hospital East , 6-5-1 Kashiwanoha, Kashiwa-shi, Chiba, 277-8577 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nobuyoshi","family":"Fukumitsu","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Kobe Proton Center , 1-6-8 Minatojima Minamimachi, Chuo-ku, Kobe 650-0047 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