title: Effect of treatment time on outcome of radiotherapy for oral tongue carcinoma.
abstract: OBJECTIVE
  To investigate the importance of total treatment time on the outcome of external beam radiotherapy (EBRT) followed by internal brachytherapy for the treatment of oral tongue carcinoma.
  
  
  METHODS
  Ninety-four patients with T1-T2N0 squamous cell carcinoma of the oral tongue were treated using 35-40 Gy EBRT followed by 35-40 Gy interstitial (137)Cs brachytherapy between 1985 and 1995. The interval between the end of EBRT and the start of interstitial treatment varied for numerous unavoidable reasons, with a mean of 25.3 days and standard deviation of 3.5 days. The median follow-up period was 59.1 months (range 6-146).
  
  
  RESULTS
  The actuarial survival rate of all cases was 78.4% at 5 years. The 5-year local control rate for those with T1 and T2 was 92.8% and 62.7%, respectively (p < 0.05). The local control rate of the primary tumor in patients with a total treatment time >43 days was statistically lower than that of patients with a total treatment time < or =43 days in all patients (p < 0.05) and in the subgroup of Stage T2 patients (p < 0.05). Multivariate analysis revealed that the local control rates in all cases were significantly related to the T stage (T2 or not), total treatment time (>43 days or not), and location of disease (posterior or not). Regression analysis for 5-year local control as a function of treatment duration showed a 2% loss of local control per day of treatment extension >30 days (r = 0.94, p < 0.01).
  
  
  CONCLUSIONS
  The total treatment time was associated with the local control rate in the RT of oral tongue carcinoma. The loss in local control was estimated to be 2.0% per additional day in our series for oral tongue carcinoma.
authors.affiliation: Department of Dental Radiology, Health Sciences University of Hokkaido, Tobetsu, Japan. hosokawa@hoku-iryo-u.ac.jp
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Hosokawa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishioka
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Ta-Chen
authors.initials: TC
authors.lastname: Chang
authors.forename: Kenji
authors.initials: K
authors.lastname: Kagei
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ohomori
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Obinata
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kaneko
authors.forename: Kazuo
authors.initials: K
authors.lastname: Miyasaka
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology* / Q000473:pathology / Q000532:radiotherapy / Q000556:secondary; D018572:Disease-Free Survival; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000532:radiotherapy; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology*; D011878:Radiotherapy / Q000379:methods; D012189:Retrospective Studies; D016019:Survival Analysis; D013997:Time Factors; D014062:Tongue Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000532:radiotherapy*; D016896:Treatment Outcome