title: Compliance to radiation therapy of head and neck cancer patients and impact on treatment outcome.
abstract: OBJECTIVE
  The aims of the study were to evaluate head and neck cancer (HNC) patient's compliance to the planned radiation therapy (RT) using the department policy established in 2005 at IPOCFG and to estimate the impact on treatment outcome due to failure in receiving RT as prescribed.
  
  
  METHODS
  359 HNC patients irradiated from 2007 to 2013 were included in this study. Patient cohort was divided into Group 1: patients receiving RT as prescribed and Group 2: patients that interrupted or suspended RT. Group Tox is the subgroup of patients that interrupted RT due to toxicity or intercurrent disease. Number and causes for treatment interruptions were assessed. The cumulative incidence of locoregional control (LRC), disease-free survival (DFS) and overall survival for Groups 1 and 2 was determined. Cox regression was performed to investigate potential hazard factors and logistic regression was made to determine risk factors related to treatment interruptions.
  
  
  RESULTS
  Major causes for treatment interruptions were toxicity plus intercurrent disease (41.7 %) and public holidays (30.1 %). 10.3 % of the patients interrupted 3-9 days. Significant differences in survival distributions of the LRC between Groups 1 and 2, of up to 19 %, were found in the subgroup of patients with N2-3 tumours, for post-operative RT and for concomitant RT. Treatment breaks larger than two days had an almost fourfold increased risk of poorer LRC and DFS.
  
  
  CONCLUSIONS
  Twin accelerators and treating on public holidays are effective measures minimizing RT breaks. For HNC, patient compliance is mostly limited by RT side-effects. Efforts to maintain RT biological effective dose in HNC must be always undertaken.
authors.affiliation: I3N Physics Department, Aveiro University, Aveiro, Portugal. bcf@estsp.ipp.pt.|School of Allied Health Technologies, Polytechnic Institute of Porto, Porto, Portugal. bcf@estsp.ipp.pt.|, Rua Valente Perfeito, 322, gab 20, 4400-330, Vila Nova de Gaia, Portugal. bcf@estsp.ipp.pt.
authors.forename: B C
authors.initials: BC
authors.lastname: Ferreira
authors.affiliation: Department of Mathematics, Center for Research and Development in Mathematics and Applications, Aveiro University, Aveiro, Portugal.
authors.forename: P
authors.initials: P
authors.lastname: Sá-Couto
authors.affiliation: Medical Physics Department, Portuguese Institute of Oncology of Coimbra Francisco Gentil, Coimbra, Portugal.
authors.forename: M C
authors.initials: MC
authors.lastname: Lopes
authors.affiliation: Radiation Therapy Department, Portuguese Institute of Oncology of Coimbra Francisco Gentil, Coimbra, Portugal.
authors.forename: L
authors.initials: L
authors.lastname: Khouri
mesh_terms: D000328:Adult; D002277:Carcinoma / Q000401:mortality / Q000532:radiotherapy; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000532:radiotherapy*; D018572:Disease-Free Survival; D005260:Female; D006258:Head and Neck Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology; D010349:Patient Compliance / Q000706:statistics & numerical data*; D011832:Radiation Injuries / Q000453:epidemiology; D000077195:Squamous Cell Carcinoma of Head and Neck
keywords: Clinical outcome; Head and neck cancer; IMRT; Radiation therapy; Treatment interruptions