title: Evaluation of a breast cancer nomogram to predict ipsilateral breast relapse after breast-conserving therapy.
abstract: A nomogram to predict for the 10-year ipsilateral breast relapse (IBR) after breast-conserving therapy (BCT) for breast cancer (BC) was developed based on the 'boost-no-boost'-trial with a concordance probability estimate (CPE) of 0.68. The aim of our study was to validate that algorithm.
  
  
  
  We retrospectively identified 1787 BC cases, treated with BCT and radiotherapy at the University Hospitals Leuven from 2000 to 2007, without missing data of the nomogram variables. Clinicopathologic factors were assessed. Validity of the prediction model was tested in terms of discrimination and calibration.
  
  
  
  Median follow-up time was 10.75years. The validation cohort differed with respect to the administration of a radiation boost, chemo- or hormonal therapy, age, tumour diameter or grade, ductal carcinoma in situ and hormone receptor positivity. On multivariable analysis, the omission of the boost was a significant prognosticator of IBR (p<0.01). The 10-year IBR-rate was 1.4%. The nomogram demonstrated suboptimal discrimination (CPE 0.54) and calibration, with an overestimation of the IBR-risk in general.
  
  
  
  The predictive model for IBR in BC is imperfect in this more recent study population.
authors.affiliation: KU Leuven - University of Leuven, Department of Oncology, Belgium; University Hospitals Leuven, Department of Radiation Oncology, Belgium. Electronic address: isabelle.kindts@uzleuven.be.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Kindts
authors.affiliation: Leuven Biostatistics and Statistical Bioinformatics Centre (L-Biostat), KU Leuven University, Belgium.
authors.forename: Annouschka
authors.initials: A
authors.lastname: Laenen
authors.affiliation: KU Leuven - University of Leuven, Department of Oncology, Belgium; University Hospitals Leuven, Department of Radiation Oncology, Belgium.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Peeters
authors.affiliation: KU Leuven - University of Leuven, Department of Oncology, Belgium; University Hospitals Leuven, Department of Radiation Oncology, Belgium.
authors.forename: Hilde
authors.initials: H
authors.lastname: Janssen
authors.affiliation: KU Leuven - University of Leuven, Department of Oncology, Belgium; University Hospitals Leuven, Department of Radiation Oncology, Belgium.
authors.forename: Tom
authors.initials: T
authors.lastname: Depuydt
authors.affiliation: KU Leuven - University of Leuven, Department of Oncology, Belgium; University Hospitals Leuven, Department of Obstetrics and Gynaecology, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Neven
authors.affiliation: KU Leuven - University of Leuven, Department of Oncology, Belgium; University Hospitals Leuven, Department of Radiation Oncology, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Van Limbergen
authors.affiliation: KU Leuven - University of Leuven, Department of Oncology, Belgium; University Hospitals Leuven, Department of Radiation Oncology, Belgium. Electronic address: caroline.weltens@uzleuven.be.
authors.forename: Caroline
authors.initials: C
authors.lastname: Weltens
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000473:pathology; D049451:Nomograms; D012189:Retrospective Studies
keywords: Breast cancer; Breast-conserving therapy; Decision making; Nomogram; Personalised medicine; Radiotherapy