title: Impact of Total Lymph Node Count on Staging and Survival After Neoadjuvant Chemoradiation Therapy for Rectal Cancer.
abstract: OBJECTIVE
  Current guidelines recommend that a minimum of 12 lymph nodes (LNs) be dissected to accurately stage rectal cancer patients. Neoadjuvant chemoradiation therapy (CRT) decreases the number of LNs retrieved at surgery. The purpose of this study was to assess the impact of the number of LNs dissected on overall survival (OS) for localized rectal cancer patients treated with neoadjuvant CRT.
  
  
  METHODS
  Treatment data were obtained on all patients treated for rectal cancer (2000-2013) in the National Oncology Data Alliance™, a proprietary database of merged tumor registries. Eligible patients were treated with neoadjuvant CRT followed by surgery and had complete data on number of positive LNs, number of LNs examined, and treatment dates (n = 4565).
  
  
  RESULTS
  Hazard ratios for OS decreased sequentially with increasing number of LNs examined until a maximum benefit was achieved with examination of eight LNs. On multivariate analysis, age, sex, race, marital status, grade, ypT stage, ypN stage, type of surgery, margin status, presence of pathologically confirmed metastasis at surgery, and number of LNs examined were significant predictors of OS.
  
  
  CONCLUSIONS
  Examination of eight or more LNs in rectal cancer patients treated with neoadjuvant CRT resulted in accurate staging and assignment into prognostic groups with an ensuing improvement in OS by stage. This study suggests that eight LNs is the threshold for an adequate lymph node dissection after neoadjuvant CRT.
authors.affiliation: Department of Radiation Oncology, City of Hope National Medical Cancer, Duarte, CA, USA. mhall@coh.org.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Hall
authors.affiliation: Department of Radiation Oncology, City of Hope National Medical Cancer, Duarte, CA, USA.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Schultheiss
authors.affiliation: Division of Biostatistics, City of Hope National Medical Cancer, Duarte, CA, USA.
authors.forename: David D
authors.initials: DD
authors.lastname: Smith
authors.affiliation: Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Cancer, Duarte, CA, USA.
authors.forename: Marwan G
authors.initials: MG
authors.lastname: Fakih
authors.affiliation: Department of Surgery, City of Hope National Medical Cancer, Duarte, CA, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, City of Hope National Medical Cancer, Duarte, CA, USA.
authors.forename: Jeffrey Y C
authors.initials: JY
authors.lastname: Wong
authors.affiliation: Department of Radiation Oncology, City of Hope National Medical Cancer, Duarte, CA, USA.
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Chen
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000628:therapy; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D059248:Chemoradiotherapy / Q000401:mortality*; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000401:mortality*; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D012004:Rectal Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000628:therapy; D015996:Survival Rate