title: A total EQD2 greater than 85 Gy for trachea and main bronchus D2cc being associated with severe late complications after definitive endobronchial brachytherapy.
abstract: OBJECTIVE
  The endobronchial brachytherapy (EBBT) is an established treatment method for tumors of the tracheobronchial system, however, little is known about the tolerance dose for organ at risk (OAR) in EBBT. The purpose of this study is to analyze patients with superficial bronchial carcinoma treated with definitive EBBT, and to investigate a relationship between late complications and dose for OAR.
  
  
  METHODS
  Endobronchial brachytherapy was performed 6 Gy per fraction for three to four fractions with or without external beam radiation therapy (EBRT). For the purpose of dosimetric analysis, the wall of the lower respiratory tract (LRT: trachea, main bronchus, and lobar bronchiole), trachea, and main bronchus (TMB) was extracted. D0.5cc, D1cc, and D2cc of LRT and TMB were calculated in each EBBT session and added together. V100, V150, and V200 of LRT were also calculated.
  
  
  RESULTS
  Between March 2008 and April 2014, EBBT was performed in 14 patients for curative intent. The 2-year overall survival (OS), progression-free survival (PFS), and local recurrence free survival (LRFS) was 82.1%, 77.9%, and 91.7%, respectively. There was one patient with grade 5, one grade 4, and three grade 3 obstruction of trachea or bronchus. The mean EQD2 of LRT D2cc, TMB D2cc, D1cc, and D0.5cc of patients with or without late severe respiratory complications was significantly different between two groups (p = 0.018, 0.008, 0.009, and 0.013, respectively). The 2-year incidence rates of late severe complications in patients with TMB D2cc ≤ 85 Gy in EQD2 and > 85 Gy were 0% and 83.3%, respectively with a statistically significance (p = 0.014).
  
  
  CONCLUSIONS
  It was discovered that TMB D2cc > 85 Gy in EQD2 is a strong risk factor for severe late respiratory complication after EBBT.
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Murakami
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Akihisa
authors.initials: A
authors.lastname: Wakita
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okamoto
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Tsuchida
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Tairo
authors.initials: T
authors.lastname: Kashihara
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Harada
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Mayuka
authors.initials: M
authors.lastname: Yamada
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Sekii
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Rei
authors.initials: R
authors.lastname: Umezawa
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Inaba
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Igaki
authors.affiliation: Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Itami
keywords: DVH; bronchial cancer; endobronchial brachytherapy; main bronchus; severe late complications