title: An algorithm for expanding the TNM staging system.
abstract: OBJECTIVE
  We describe a new method to expand the tumor, lymph node, metastasis (TNM) staging system using a clustering algorithm. Cases of breast cancer were used for demonstration.
  
  
  METHODS
  An unsupervised ensemble-learning algorithm was used to create dendrograms. Cutting the dendrograms produced prognostic systems.
  
  
  RESULTS
  Prognostic systems contained groups of patients with similar outcomes. The prognostic systems based on tumor size and lymph node status recapitulated the general structure of the TNM for breast cancer. The prognostic systems based on tumor size, lymph node status, histologic grade and estrogen receptor status revealed a more detailed stratification of patients when grade and estrogen receptor status were added.
  
  
  CONCLUSIONS
  Prognostic systems from cutting the dendrogram have the potential to improve and expand the TNM.
authors.affiliation: Department of Preventive Medicine & Biostatistics, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD 20814, USA.
authors.forename: Dechang
authors.initials: D
authors.lastname: Chen
authors.affiliation: Surgical Oncology, John P Murtha Cancer Center, Walter Reed National Military Medical Center, 8901 Wisconsin Ave., Bethesda, MD 20889, USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Hueman
authors.affiliation: Department of Preventive Medicine & Biostatistics, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD 20814, USA.|Department of Surgery, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD 20814, USA.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Henson
authors.affiliation: Department of Pathology, The George Washington University Medical Center, Washington, DC 20037, USA.|Department of Surgery, The George Washington University Medical Center, Washington, DC 20037, USA.
authors.forename: Arnold M
authors.initials: AM
authors.lastname: Schwartz
mesh_terms: D000465:Algorithms; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000401:mortality; D016000:Cluster Analysis; D003198:Computer Simulation; D005260:Female; D006801:Humans; D060787:Neoplasm Grading; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging / Q000379:methods*; D011379:Prognosis; D018426:SEER Program
chemical_list: D014408:Biomarkers, Tumor
keywords: TNM; breast cancer; dendrogram; ensemble learning; hierarchical clustering; prognostic system; survival