title: Validation of a Web-Based Tool to Predict the Ipsilateral Breast Tumor Recurrence (IBTR! 2.0) after Breast-Conserving Therapy for Korean Patients.
abstract: OBJECTIVE
  IBTR! 2.0 is a web-based nomogram that predicts the 10-year ipsilateral breast tumor recurrence (IBTR) rate after breast-conserving therapy. We validated this nomogram in Korean patients.
  
  
  METHODS
  The nomogram was tested for 520 Korean patients, who underwent breast-conserving surgery followed by radiation therapy. Predicted and observed 10-year outcomes were compared for the entire cohort and for each group, predefined by nomogram-predicted risks: group 1, <3%; group 2, 3% to 5%; group 3, 5% to 10%; group 4, >10%.
  
  
  RESULTS
  In overall patients, the overall 10 year predicted and observed estimates of IBTR were 5.22% and 5.70% (p=0.68). In group 1, (n=124), the predicted and observed estimates were 2.25% and 1.80% (p=0.73), in group 2 (n=177), 3.95% and 3.90% (p=0.97), in group 3 (n=181), 7.14% and 8.80% (p=0.42), and in group 4 (n=38), 11.66% and 14.90% (p=0.73), respectively.
  
  
  CONCLUSIONS
  In a previous validation of this nomogram based on American patients, nomogram-predicted IBTR rates were overestimated in the high-risk subgroup. However, our results based on Korean patients showed that the observed IBTR was higher than the predicted estimates in groups 3 and 4. This difference may arise from ethnic differences, as well as from the methods used to detect IBTR and the healthcare environment. IBTR! 2.0 may be considered as an acceptable nomogram in Korean patients with low- to moderate-risk of in-breast recurrence. Before widespread use of this nomogram, the IBTR! 2.0 needs a larger validation study and continuous modification.
authors.affiliation: Division of Breast and Endocrine Surgery, Department of Surgery, Korea University Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Seung Pil
authors.initials: SP
authors.lastname: Jung
authors.forename: Sung Mo
authors.initials: SM
authors.lastname: Hur
authors.forename: Se Kyung
authors.initials: SK
authors.lastname: Lee
authors.forename: Sangmin
authors.initials: S
authors.lastname: Kim
authors.forename: Min-Young
authors.initials: MY
authors.lastname: Choi
authors.forename: Soo Youn
authors.initials: SY
authors.lastname: Bae
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Kim
authors.forename: Min Kuk
authors.initials: MK
authors.lastname: Kim
authors.forename: Won Ho
authors.initials: WH
authors.lastname: Kil
authors.forename: Jun-Ho
authors.initials: JH
authors.lastname: Choe
authors.forename: Jung-Han
authors.initials: JH
authors.lastname: Kim
authors.forename: Jee Soo
authors.initials: JS
authors.lastname: Kim
authors.forename: Seok Jin
authors.initials: SJ
authors.lastname: Nam
authors.forename: Jeoung Won
authors.initials: JW
authors.lastname: Bae
authors.forename: Jeong Eon
authors.initials: JE
authors.lastname: Lee
keywords: Breast neoplasms; Nomograms; Radiotherapy; Recurrence; Validation studies