title: Modeling the effect of tumor size in early breast cancer.
abstract: BACKGROUND
  The purpose of this study was to determine the type of relationship between tumor size and mortality in early breast carcinoma.
  
  
  METHODS
  The data was abstracted from 83,686 cases registered in the Surveillance, Epidemiology, and End Results Program of women diagnosed with primary breast carcinoma between 1988 and 1997 presenting with a T1-T2 lesion and no metastasis in whom axillary node dissection was performed: 58,070 women were node-negative (N0) and 25,616 were node-positive (N+). End point was death from any cause. Tumor size was modeled as a continuous variable by proportional hazards using a generalized additive models procedure.
  
  
  RESULTS
  Functionally, a Gompertzian expression exp(-exp(-(size-15)/10)) provided a good fit to the effect of tumor size (in millimeters) on mortality, irrespective of nodal status. Quantitatively, for tumor size between 3 and 50 mm, the increase of crude cumulative death rate (number of observed deaths divided by the number of patients at risk) increased with size from 10% to 25% for N0 and from 20% to 40% for N+.
  
  
  CONCLUSIONS
  The functional relationship of tumor size with mortality is concordant with current knowledge of tumor growth. However, its qualitative and quantitative independence of nodal status is in contradiction with the prevailing concept of sequential disease progression from primary tumor to regional nodes. This argues against the perception that nodal metastases are caused by the primary tumor.
authors.affiliation: Division of Hematology Oncology, Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131, USA. cverschraegen@salud.unm.edu
authors.forename: Claire
authors.initials: C
authors.lastname: Verschraegen
authors.forename: Vincent
authors.initials: V
authors.lastname: Vinh-Hung
authors.forename: Gábor
authors.initials: G
authors.lastname: Cserni
authors.forename: Richard
authors.initials: R
authors.lastname: Gordon
authors.forename: Melanie E
authors.initials: ME
authors.lastname: Royce
authors.forename: Georges
authors.initials: G
authors.lastname: Vlastos
authors.forename: Patricia
authors.initials: P
authors.lastname: Tai
authors.forename: Guy
authors.initials: G
authors.lastname: Storme
mesh_terms: D001943:Breast Neoplasms / Q000401:mortality* / Q000473:pathology*; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D018570:Risk Assessment; D018426:SEER Program; D016019:Survival Analysis