title: A nodal positivity constant: new perspectives in lymph node evaluation and colorectal cancer.
abstract: OBJECTIVE
  To date, associations between the number of lymph nodes evaluated, staging, and survival have been examined in the context of large population-based studies conducted by a small number of investigators. Therefore, although high-quality data are available, perspective is lacking.
  
  
  METHODS
  Studies for this paper were identified by searches of Medline, Scopus, PubMed, and manual searching of references from articles, using the search terms ''colorectal cancer'', ''nodal status'' and ''lymph node''.
  
  
  RESULTS
  It is clear that survival benefit increases with the increasing number of lymph nodes harvested. Despite this observation, there has been no significant increase in the proportion of node-positive cancers over the past two decades.
  
  
  CONCLUSIONS
  The nodal positivity rate for colorectal cancer consistently approximates 40 % across a wide range of studies internationally, a phenomenon that has not previously been recognized in the literature. We review the evidence and introduce the concept of a nodal positivity constant.
authors.affiliation: Institute for Clinical Outcomes Research and Education (iCORE), St. Vincent's University Hospital, Elm Park, Dublin 4, Ireland. niamhogan@gmail.com
authors.forename: Niamh M
authors.initials: NM
authors.lastname: Hogan
authors.forename: Desmond C
authors.initials: DC
authors.lastname: Winter
mesh_terms: D000005:Abdomen; D003082:Colectomy; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D009367:Neoplasm Staging