title: The effect of simulation on recurrence after breast-conserving surgery and radiotherapy: preliminary results.
abstract: OBJECTIVE
  To evaluate the effect of the simulation method on recurrence among the patients who received radiotherapy after breast-conserving surgery (BCS) for early breast carcinoma.
  
  
  METHODS
  Between 1995 and 2000, 70 patients with stage I-II breast carcinoma underwent breast-conserving surgery and adjuvant radiotherapy. Twenty nine patients (41.4%) were simulated with the 2D contour-based method (September 1995 to August 1997) and 41 patients (58.6%) were simulated with the 3D CT-based method (September 1997 to February 2000). To analyze the effect of the simulation method, the patient and treatment characteristics were compared.
  
  
  RESULTS
  The characteristics were similar for the patients between the 2D contour-based simulation group and the 3D CT-based simulation group. During a median follow-up period of 75 months, 4 (13.8%) of 29 patients who were treated with 2D simulation and 1 (2.4%) of 41 patients who were treated with 3D simulation group developed treatment failure. The five-year survival rates were 89.2% and 95.1% between the 2D and 3D simulation groups (p=0.196). The five-year disease free survival (DFS) rates were 86.2% and 97.5% between the 2D and 3D simulation groups (p=0.0636). On univariate analysis, age > 40 (p= 0.0226) and the number of dissected axillary lymph node >or= 10 (p=0.0435) were independent predictors of improved 5-year DFS.
  
  
  CONCLUSIONS
  Although our data showed marginal significance for the DFS between the two groups, it is insufficient, due to the small number of patients in our study, to prove whether 3D CT-based simulation might improve the DFS and reduce the risk of recurrence when compared with 2D contour-based simulation. Further study is needed with a larger group of patients.
authors.affiliation: Department of Radiation Oncology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Ji-Yoon
authors.initials: JY
authors.lastname: Kim
authors.forename: Yeon-Sil
authors.initials: YS
authors.lastname: Kim
authors.forename: Mi-Ryung
authors.initials: MR
authors.lastname: Ryu
authors.forename: Sung-Whan
authors.initials: SW
authors.lastname: Kim
authors.forename: Chul-Seung
authors.initials: CS
authors.lastname: Kay
authors.forename: Sei-Chul
authors.initials: SC
authors.lastname: Yoon
authors.forename: Woo-Chan
authors.initials: WC
authors.lastname: Park
authors.forename: Byung-Joo
authors.initials: BJ
authors.lastname: Song
authors.forename: Se-Jeong
authors.initials: SJ
authors.lastname: Oh
authors.forename: Sang-Seol
authors.initials: SS
authors.lastname: Jung
authors.forename: Jong-Man
authors.initials: JM
authors.lastname: Won
authors.forename: Seung-Nam
authors.initials: SN
authors.lastname: Kim
authors.forename: Su-Mi
authors.initials: SM
authors.lastname: Chung