title: The Impact of the Overall Radiotherapy Time on Clinical Outcome of Patients with Nasopharyngeal Carcinoma; A Retrospective Study.
abstract: OBJECTIVE
  In Yogyakarta, nasopharyngeal carcinoma (NPC) shows a poor response to radiotherapy treatment. Previous study showed a prolonged overall treatment time (OTT), due to interruptions during treatment. This study explores the association between clinical outcome and OTT. Secondary, the relation between clinical outcome and disease stage, waiting time to radiation (WT) and chemotherapy schedule was explored.
  
  
  METHODS
  In this retrospective cohort, 142 patients who started curative intent radiotherapy for NPC between March 2009 and May 2014, with or without chemotherapy, were included. The median follow up time was 1.9 years. Data was collected on WT, OTT, disease stage, and chemotherapy schedule. Time factors were log-transformed. Clinical outcome was defined as therapy response, loco-regional control (LRC), disease free survival (DFS) and overall survival (OS).
  
  
  RESULTS
  The median WT was 117 days (range 12-581) and OTT was 58 days (43-142). OTT and disease stage were not associated to any of the clinical outcome parameters. The log-WT was associated to poor therapy outcome (HR 1.68; 95% ci: 1.09-2.61), LRC (HR 1.66; 95% ci: 1.15-2.39), and DFS (HR 1.4; 95% ci: 1.09-1.81). In the multivariable analysis, significant hazard risk for poor therapy response, LRC, DFS and OS were seen for patients who didn't received concurrent chemotherapy.
  
  
  CONCLUSIONS
  Not receiving concurrent chemotherapy showed the strongest risk for poor outcome. Since the choice of chemotherapy is related to a variety of factors, like the WT and patient's physical condition when radiation can start, careful interpretation is needed. Reason for not finding a relation between OTT and clinical outcome might be the low number of patients who finished radiotherapy within 7 weeks, or by a stronger detrimental effect of other factors.
authors.affiliation: Department of Head and Neck Surgery and Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.|Department of Otolaryngology-Head and Neck Surgery, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: S D
authors.initials: SD
authors.lastname: Stoker
authors.affiliation: Department of Head and Neck Surgery and Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Fles
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Gadjah Mada University, Dr. Sardjito hospital, Yogyakarta, Indonesia.
authors.forename: C
authors.initials: C
authors.lastname: Herdini
authors.affiliation: Department of Head and Neck Surgery and Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: F J F
authors.initials: FJ
authors.lastname: Rijntjes
authors.affiliation: Department of Radiotherapy, Gadjah Mada University, Dr. Sardjito hospital, Yogyakarta, Indonesia.
authors.forename: M
authors.initials: M
authors.lastname: Tjokronagoro
authors.affiliation: Department of Radiotherapy, Gadjah Mada University, Dr. Sardjito hospital, Yogyakarta, Indonesia.
authors.forename: S R
authors.initials: SR
authors.lastname: Dwidanarti
authors.affiliation: Department of Bioinformatics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Sikorska
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: C R
authors.initials: CR
authors.lastname: Leemans
authors.affiliation: Department of Psychosocial Research and Epidemiology, The Netherlands Cancer Institute, Amsterdam, the Netherlands.|Department of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, the Netherlands.
authors.forename: M K
authors.initials: MK
authors.lastname: Schmidt
authors.affiliation: Department of Radiotherapy, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Al-Mamgani
authors.affiliation: Department of Head and Neck Surgery and Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.|Department of Otorhinolaryngology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: Wildeman
authors.affiliation: Department of Histology, Cell and Tumour Biology, Faculty of Medicine, Gadjah Mada University, Yogyakarta, Indonesia.
authors.forename: S M
authors.initials: SM
authors.lastname: Haryana
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Gadjah Mada University, Dr. Sardjito hospital, Yogyakarta, Indonesia.
authors.forename: S R
authors.initials: SR
authors.lastname: Indrasari
authors.affiliation: Department of Head and Neck Surgery and Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.|Department of Otolaryngology-Head and Neck Surgery, Gadjah Mada University, Dr. Sardjito hospital, Yogyakarta, Indonesia.|Department of Oral and Maxillofacial Surgery, Academic medical Centre, Amsterdam, The Netherlands.
authors.forename: I B
authors.initials: IB
authors.lastname: Tan
mesh_terms: D002277:Carcinoma; D018572:Disease-Free Survival; D005260:Female; D006258:Head and Neck Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D015996:Survival Rate