title: Impact of number of nodes retrieved on outcome in patients with rectal cancer.
abstract: OBJECTIVE
  We postulated that the pathologic evaluation of the lymph nodes of surgical specimens from patients with rectal cancer can have a substantial impact on time to relapse and survival.
  
  
  METHODS
  We analyzed data from 1,664 patients with T3, T4, or node-positive rectal cancer treated in a national intergroup trial of adjuvant therapy with chemotherapy and radiation therapy. Associations between the number of lymph nodes found by the pathologist in the surgical specimen and the time to relapse and survival outcomes were investigated.
  
  
  RESULTS
  Patients were divided into groups by nodal status and the corresponding quartiles of numbers of nodes examined. The number of nodes examined was significantly associated with time to relapse and survival among patients who were node-negative. For the first through fourth quartiles, the 5-year relapse rates were 0.37, 0.34, 0.26, and 0.19 (P: = .003), and the 5-year survival rates were 0.68, 0.73, 0.72, and 0.82 (P: = .02). No significant differences were found by quartiles among patients determined to be node-positive. We propose that observed differences are primarily related to the incorrect determination of nodal status in node-negative patients. Approximately 14 nodes need to be studied to define nodal status accurately.
  
  
  CONCLUSIONS
  These results suggest that the pathologic assessment of lymph nodes in surgical specimens is often inaccurate and that examining greater number of nodes increases the likelihood of proper staging. Some patients who might benefit from adjuvant therapy are misclassified as node-negative due to incomplete sampling of lymph nodes.
authors.affiliation: Department of Radiation Oncology, University of North Carolina, Chapel Hill 27599-7512, USA. tepper@radonc.unc.edu
authors.forename: J E
authors.initials: JE
authors.lastname: Tepper
authors.forename: M J
authors.initials: MJ
authors.lastname: O'Connell
authors.forename: D
authors.initials: D
authors.lastname: Niedzwiecki
authors.forename: D
authors.initials: D
authors.lastname: Hollis
authors.forename: C
authors.initials: C
authors.lastname: Compton
authors.forename: A B
authors.initials: AB
authors.lastname: Benson
authors.forename: B
authors.initials: B
authors.lastname: Cummings
authors.forename: L
authors.initials: L
authors.lastname: Gunderson
authors.forename: J S
authors.initials: JS
authors.lastname: Macdonald
authors.forename: R J
authors.initials: RJ
authors.lastname: Mayer
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001706:Biopsy / Q000379:methods*; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods*; D008207:Lymphatic Metastasis; D011379:Prognosis; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D018709:Statistics, Nonparametric; D015996:Survival Rate; D016896:Treatment Outcome