title: A validated web-based nomogram for predicting positive surgical margins following breast-conserving surgery as a preoperative tool for clinical decision-making.
abstract: BACKGROUND
  Breast-conserving therapy, consisting of lumpectomy and adjuvant radiotherapy, is considered standard treatment for early-stage breast cancer. One of the most important risk factors of local recurrence is the presence of positive surgical margins following lumpectomy. We aimed to develop and validate a predictive model (nomogram) to predict for positive margins following the first attempt at lumpectomy as a preoperative tool for clinical decision-making.
  
  
  METHODS
  Patients with clinical T1-2N0-1Mx-0 histology-proven invasive breast carcinoma who underwent BCT throughout the North-East region of The Netherlands between June 2008 and July 2009 were selected from the Netherlands Cancer Registry (n = 1185). Results from multivariate logistic regression analyses served as the basis for development of the nomogram. Nomogram calibration and discrimination were assessed graphically and by calculation of a concordance index, respectively. Nomogram performance was validated on an external independent dataset (n = 331) from the University Medical Center Groningen.
  
  
  RESULTS
  The final multivariate regression model included clinical, radiological, and pathological variables. Concordance indices were calculated of 0.70 (95% CI: 0.66-0.74) and 0.69 (95% CI: 0.63-0.76) for the modeling and the validation group, respectively. Calibration of the model was considered adequate in both groups. A nomogram was developed as a graphical representation of the model. Moreover, a web-based application (http://www.breastconservation.com) was build to facilitate the use of our nomogram in a clinical setting.
  
  
  CONCLUSIONS
  We developed and validated a nomogram that enables estimation of the preoperative risk of positive margins in breast-conserving surgery. Our nomogram provides a valuable tool for identifying high-risk patients who might benefit from preoperative MRI and/or oncoplastic surgery.
authors: Department of Surgery, University Medical Center Groningen, Groningen, The Netherlands.
authors: Rick G
authors: RG
authors: Pleijhuis
authors: Annemiek B G
authors: AB
authors: Kwast
authors: Liesbeth
authors: L
authors: Jansen
authors: Jakob
authors: J
authors: de Vries
authors: Rosanne
authors: R
authors: Lanting
authors: Joost
authors: J
authors: Bart
authors: Theo
authors: T
authors: Wiggers
authors: Gooitzen M
authors: GM
authors: van Dam
authors: Sabine
authors: S
authors: Siesling
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000150:complications / Q000473:pathology* / Q000628:therapy*; D002114:Calcinosis / Q000150:complications; D002277:Carcinoma / Q000150:complications / Q000473:pathology* / Q000628:therapy*; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D020407:Internet; D008279:Magnetic Resonance Imaging; D015412:Mastectomy, Segmental; D008875:Middle Aged; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D049451:Nomograms; D057234:Preoperative Period; D018714:Radiotherapy, Adjuvant
keywords: AUROC; BCT; Breast cancer; Breast-conserving surgery; CNB; LR; MVA; Nomogram; OR; Surgical margin status; area under the receiver-operating characteristic curve; breast-conserving therapy; core needle biopsy; local recurrence; multivariate regression analysis; odds ratio