title: High-dose-rate brachytherapy boost for prostate cancer: Analysis of dose-volume histogram parameters for predicting late rectal toxicity.
abstract: To determine the significance of dose-volume histogram parameters for predicting late rectal toxicity (LRT) after single-fraction high-dose-rate brachytherapy (HDRBT) boost and external beam radiotherapy (EBRT) in prostate cancer.
  
  
  
  Three hundred patients with intermediate- or high-risk prostate cancer were included between August 2010 and March 2015. Treatment comprised a single-fraction HDRBT boost of 15.0 Gy plus EBRT (46.0 Gy delivered in 23 fractions) or an HDRBT boost of 9.5 Gy plus EBRT (60.0 Gy delivered in 30 fractions) if the seminal vesicles were infiltrated using real-time transrectal ultrasound-based planning. LRT was evaluated every 3 months after the end of the combined treatment using the Common Terminology Criteria for Adverse Events, version 4.0. The minimum dose received by the most exposed 0.1 and 2.0 cm3volume of the rectum (D0.1 cc/D2cc) was analyzed by estimating the biologically equivalent rectal dose according to the recommendations of the Groupe Européen de Curiethérapie/European Society for Radiotherapy and Oncology and an ordinal regression analysis was performed.
  
  
  
  LRT was observed in 62 patients (20.7%) at a median followup of 33 (range, 2-68) months. Twenty patients (6.7%) developed grade 2 and 3 patients (1%) developed grade 3 LRT. A significant association was observed between D2cc and the probability of developing grade 1-3 LRT (p = 0.04).
  
  
  
  D2cc is associated with the occurrence of LRT in HDRBT-treated prostate cancer patients. The dose constraints proposed and recommended by experienced HDRBT centers must be investigated to determine the threshold dose through long-term and prospective studies.
authors.affiliation: Doctoral School, "San Vicente Mártir" Catholic University of Valencia, Valencia, Spain; Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain; Department of Radiation Oncology, Recoletas Oncology Institute, Campo Grande Hospital, Valladolid, Spain. Electronic address: rchicas@ufm.edu.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Chicas-Sett
authors.affiliation: Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain.
authors.forename: Dolores
authors.initials: D
authors.lastname: Farga
authors.affiliation: Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Perez-Calatayud
authors.affiliation: Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Celada
authors.affiliation: Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Roldan
authors.affiliation: Department of Biostatistics, La Fe Health Research Institute, Valencia, Spain.
authors.forename: Victoria
authors.initials: V
authors.lastname: Fornes-Ferrer
authors.affiliation: Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain.
authors.forename: Blanca
authors.initials: B
authors.lastname: Ibanez-Rosello
authors.affiliation: Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Tormo
authors.affiliation: Institute for Instrumentation in Molecular Imaging, i3M-CSIC, Universidad Politécnica de Valencia, Valencia, Spain.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Benlloch
authors.affiliation: Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain; Medical Physics Research Group La Fe - UVEG, IRIMED, Valencia, Spain.
authors.forename: Jose
authors.initials: J
authors.lastname: Perez-Calatayud
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D003131:Combined Modality Therapy; D019583:Dose Fractionation, Radiation; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk / Q000528:radiation effects*; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology*; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum / Q000528:radiation effects*; D012044:Regression Analysis; D013997:Time Factors
keywords: Biologically equivalent dose; Dose-volume histogram parameter; High-dose-rate brachytherapy boost; Late rectal toxicity; Organ at risk; Prostate cancer