title: Head and neck adaptive radiotherapy: Predicting the time to replan.
abstract: OBJECTIVE
  Head and neck (H&N) cancer patients can undergo anatomical change throughout radiotherapy treatment. Adaptive radiotherapy (ART) is effective in addressing the impact of this change on the planned dose distribution. The aim of this study was to identify pretreatment factors that influence the need for and timing of replanning for patients receiving chemoradiotherapy for node-positive nasopharyngeal (NPC) and oropharyngeal carcinoma (OPC).
  
  
  METHODS
  Of 110 patients enrolled in a prospective H&N ART study, 21 (19%) underwent a second planning scan (re-CT) and were included in this review. Univariate and multivariate analysis was used to compare those patients who were replanned with those that were not. Factors influencing the timing of replanning were assessed including patient and tumor characteristics and structure volume details.
  
  
  RESULTS
  Of the five replanned patients, three were diagnosed with NPC (P = 0.06) and had significantly larger initial nodal volumes (median volume 140.3 cc vs. 39.1 cc, P = 0.019). Overall the median time of re-CT was significantly different between replanned and non-replanned patients, with replanned patients having an earlier re-CT: median fraction 18 versus fraction 23 (P = 0.01). Specifically, NPC patients who were replanned had a re-CT performed earlier than OPC patients (median fraction 11 vs. 20).
  
  
  CONCLUSIONS
  For H&N patients with large nodes receiving definitive chemoradiotherapy, replanning may be considered at the commencement of week 3 for NPC patients and in week 4 of treatment for OPC patients. This information may facilitate a forward planning approach to H&N ART that enables allocation of departmental resources prior to treatment commencement.
authors.affiliation: Radiation Oncology Department, Princess Alexandra Hospital, Brisbane, Queensland, Australia.|Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Brown
authors.affiliation: Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Owen
authors.affiliation: Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Fiona
authors.initials: F
authors.lastname: Harden
authors.affiliation: Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Kerrie
authors.initials: K
authors.lastname: Mengersen
authors.affiliation: Radiation Oncology Department, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
authors.forename: Kimberley
authors.initials: K
authors.lastname: Oestreich
authors.affiliation: Radiation Oncology Department, Radiation Oncology Mater Centre, Brisbane, Queensland, Australia.
authors.forename: Whitney
authors.initials: W
authors.lastname: Houghton
authors.affiliation: Radiation Oncology Department, Radiation Oncology Mater Centre, Brisbane, Queensland, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Poulsen
authors.affiliation: Radiation Oncology Department, Royal Brisbane and Women's, Brisbane, Queensland, Australia.
authors.forename: Selina
authors.initials: S
authors.lastname: Harris
authors.affiliation: Radiation Oncology Department, Royal Brisbane and Women's, Brisbane, Queensland, Australia.
authors.forename: Charles
authors.initials: C
authors.lastname: Lin
authors.affiliation: Radiation Oncology Department, Princess Alexandra Hospital, Brisbane, Queensland, Australia.|School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Sandro
authors.initials: S
authors.lastname: Porceddu
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000556:secondary / Q000628:therapy*; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy*; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy*; D011446:Prospective Studies; D011880:Radiotherapy Planning, Computer-Assisted; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
keywords: adaptive; head and neck cancer; radiotherapy