title: Impact of concurrent androgen deprivation on fiducial marker migration in external-beam radiation therapy for prostate cancer.
abstract: OBJECTIVE
  To determine the extent of gold fiducial marker (FM) migration in patients treated for prostate cancer with concurrent androgen deprivation and external-beam radiation therapy (EBRT).
  
  
  METHODS
  Three or 4 gold FMs were implanted in 37 patients with prostate adenocarcinoma receiving androgen deprivation therapy (ADT) in conjunction with 70-78 Gy. Androgen deprivation therapy was started a median of 3.9 months before EBRT (range, 0.3-12.5 months). To establish the extent of FM migration, the distance between each FM was calculated for 5-8 treatments once per week throughout the EBRT course. For each treatment, the distance between FMs was compared with the distance from the digitally reconstructed radiographs generated from the planning CT. A total of 281 treatments were analyzed.
  
  
  RESULTS
  The average daily migration was 0.8 ± 0.3 mm, with distances ranging from 0.2 mm-2.6 mm. Two of the 281 assessed treatments (0.7%) showed migrations >2 mm. No correlation between FM migration and patient weight or time delay between ADT and start of EBRT was found. There was no correlation between the extent of FM migration and prostate volume.
  
  
  CONCLUSIONS
  This is the largest report of implanted FM migration in patients receiving concomitant ADT. Only 0.7% of the 281 treatments studied had significant marker migrations (>2 mm) throughout the course of EBRT. Consequently, the use of implanted FMs in these patients enables accurate monitoring of prostate gland position during treatment.
authors.affiliation: Département de Radio-Oncologie, Centre hospitalier de l'Université de Montréal-Hôpital Notre-Dame, Montréal, Quebec, Canada.
authors.forename: David A
authors.initials: DA
authors.lastname: Tiberi
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Carrier
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Beauchemin
authors.forename: Thu Van
authors.initials: TV
authors.lastname: Nguyen
authors.forename: Dominic
authors.initials: D
authors.lastname: Béliveau-Nadeau
authors.forename: Daniel
authors.initials: D
authors.lastname: Taussky
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy; D000726:Androgen Antagonists / Q000627:therapeutic use*; D003131:Combined Modality Therapy / Q000379:methods; D057918:Fiducial Markers; D005548:Foreign-Body Migration / Q000000981:diagnostic imaging; D006046:Gold; D006801:Humans; D008297:Male; D011467:Prostate / Q000000981:diagnostic imaging / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted
chemical_list: D000726:Androgen Antagonists; D006046:Gold