title: Re-irradiation for locoregionally recurrent tumors of the thorax: a single-institution, retrospective study.
abstract: BACKGROUND
  Re-irradiation (re-RT) of the thorax is challenging due to the impact of prior therapies on normal tissues, and there are few reports of definitive re-RT. The treatment toxicities and efficacy of re-RT are not well known. The aim of the present study was to assess the safety and efficacy of definitive re-RT of the thorax.
  
  
  METHODS
  Patients who were treated with thoracic re-RT between March 2007 and December 2014 were retrospectively analyzed. Primary and re-irradiation plans were required to have an overlap of dose distributions for the 80 % isodose level. All doses were recalculated to an equivalent dose of 2 Gy per fraction (EQD2). When possible, analysis of dose accumulation was carried out using the medical image merge (MIM) (®) software program (version 6.5, MIM Software Inc., Cleveland, OH). Administration dosages for organs at risk were defined.
  
  
  RESULTS
  Fourteen (67 %) and seven (33 %) patients with non-small cell carcinoma (NSCLC) and small cell carcinoma (SCLC), respectively, were identified. The patients' median age was 72 (range 53-85) years. Fifteen patients (71 %) had "proximal" tumors, defined as tumors at the distal 2 cm of the trachea, carina, and main bronchi. The median interval from initial RT to re-RT was 26.8 (range 11.4-92.3) months. Re-RT was delivered by X-ray beam and proton beam therapy in 20 (95 %) patients and 1 (5 %) patient, respectively. The median radiation dose of re-RT was 60 (range 54-87.5) Gy10 and 50 (range 50.0-87.5) Gy10 for patients with NSCLC and SCLC, respectively. Grade 3 acute radiation pneumonitis occurred in only one patient. There were no other serious complications. The median follow-up time was 22.1 (range 2.3-56.4) months. The median local progression-free survival time (LPFS) and overall survival time (OS) were 12.9 (95 % confidence interval (CI): 8.9-27.9) months and 31.4 (95 % CI: 16.9-45.9) months, respectively. Patients receiving ≥ 60 Gy10 at re-RT had longer LPFS (p = 0.04).
  
  
  CONCLUSIONS
  Good safety with longer OS than in previous reports was demonstrated. Re-RT seems to be a promising treatment option. Further study to define the risk-benefit ratios is necessary.
authors.affiliation: Radiation and Proton Therapy Center, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-8777, Japan. sumitkiy@hirakata.kmu.ac.jp.|Department of Radiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakatashi, Osaka, 573-1010, Japan. sumitkiy@hirakata.kmu.ac.jp.
authors.forename: Kiyomi
authors.identifier: http://orcid.org/0000-0002-3478-5681
authors.initials: K
authors.lastname: Sumita
authors.affiliation: Radiation and Proton Therapy Center, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-8777, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Harada
authors.affiliation: Radiation and Proton Therapy Center, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-8777, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Asakura
authors.affiliation: Radiation and Proton Therapy Center, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-8777, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ogawa
authors.affiliation: Radiation and Proton Therapy Center, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-8777, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Onoe
authors.affiliation: Radiation and Proton Therapy Center, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-8777, Japan.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Murayama
authors.affiliation: Department of Radiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakatashi, Osaka, 573-1010, Japan.
authors.forename: Satoaki
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Radiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakatashi, Osaka, 573-1010, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Tanigawa
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-8777, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Radiation and Proton Therapy Center, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-8777, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nishimura
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000532:radiotherapy; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy; D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000532:radiotherapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000532:radiotherapy*; D009367:Neoplasm Staging; D058958:Organs at Risk / Q000528:radiation effects*; D011379:Prognosis; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D000069475:Re-Irradiation; D012189:Retrospective Studies; D055752:Small Cell Lung Carcinoma / Q000473:pathology / Q000532:radiotherapy; D015996:Survival Rate; D013899:Thoracic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D014132:Trachea / Q000528:radiation effects
keywords: Lung cancer; Re-irradiation; Recurrence tumor