title: Predicting likelihood of having four or more positive nodes in patient with sentinel lymph node-positive breast cancer: a nomogram validation study.
abstract: OBJECTIVE
  Katz suggested a nomogram for predicting having four or more positive nodes in sentinel lymph node (SLN)-positive breast cancer patients. The findings from this formula might influence adjuvant radiotherapy decisions. Our goal was to validate the accuracy of the Katz nomogram.
  
  
  METHODS
  We reviewed the records of 309 patients with breast cancer who had undergone completion axillary lymph node dissection. The factors associated with the likelihood of having four or more positive axillary nodes were evaluated in patients with one to three positive SLNs. The nomogram developed by Katz was applied to our data set. The area under the curve of the corresponding receiver operating characteristics curve was calculated for the nomogram.
  
  
  RESULTS
  Of the 309 patients, 80 (25.9%) had four or more positive axillary lymph nodes. On multivariate analysis, the number of positive SLNs (p < .0001), overall metastasis size (p = .019), primary tumor size (p = .0001), and extracapsular extension (p = .01) were significant factors predicting for four or more positive nodes. For patients with <5% probability, 90.3% had fewer than four positive nodes and 9.7% had four or more positive nodes. The negative predictive value was 91.7%, and sensitivity was 80%. The nomogram was accurate and discriminating (area under the curve, .801).
  
  
  CONCLUSIONS
  The probability of four or more involved nodes is significantly greater in patients who have an increased number of positive SLNs, increased overall metastasis size, increased tumor size, and extracapsular extension. The Katz nomogram was validated in our patients. This nomogram will be helpful to clinicians making adjuvant treatment recommendations to their patients.
authors.affiliation: Department of Surgical Oncology, Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
authors.forename: Bulent
authors.initials: B
authors.lastname: Unal
authors.forename: Akif Serhat
authors.initials: AS
authors.lastname: Gur
authors.forename: Sushil
authors.initials: S
authors.lastname: Beriwal
authors.forename: Gong
authors.initials: G
authors.lastname: Tang
authors.forename: Ronald
authors.initials: R
authors.lastname: Johnson
authors.forename: Gretchen
authors.initials: G
authors.lastname: Ahrendt
authors.forename: Marguerite
authors.initials: M
authors.lastname: Bonaventura
authors.forename: Atilla
authors.initials: A
authors.lastname: Soran