title: Influence of age and site of disease on lymph node yield in colorectal cancer.
abstract: OBJECTIVE
  Colorectal cancer (CRC) is the second-leading cause of cancer death in New Zealand. Lymph node yield (LNY) is an independent prognostic factor in CRC and 12 or more lymph nodes in the resected specimen is the current recommended standard, regardless of age or site of disease. The aim of this study was to examine the effect of age and site of the disease on LNY.
  
  
  METHODS
  Patients undergoing elective surgery for CRC at Dunedin Hospital between 1995 and 2012, who enrolled in studies involving prospective data and tissue collection, were included in the current study. The relationship between LNY and demographic and pathological variables including age, sex, tumour location and stage were investigated.
  
  
  RESULTS
  824 patients were included (mean age 70.5 years, 51% female). The mean (SD) LNY was 17.9 (10.1).There was a weak but significant negative correlation between age and LNY (r=-0.08; p=0.024) that was more evident in patients with right-sided tumours (r=0.18; p=0.001). Right-sided tumours also had a higher LNY (mean 20.5) than left colon (mean 16.8) and rectal cancer (mean 14.6) (p<0.001). Overall the mean LNY reduced by 1 for every 7 years advancement in age.
  
  
  CONCLUSIONS
  LNY is higher in right-sided colon cancer and reduces with age. Further research should consider whether the recommended standard for LNY in the specimen should take account of age and tumour location.
authors.forename: Omid
authors.initials: O
authors.lastname: Ahmadi
authors.forename: Mark D
authors.initials: MD
authors.lastname: Stringer
authors.forename: Michael A
authors.initials: MA
authors.lastname: Black
authors.affiliation: Department of Surgical Sciences, Dunedin School of Medicine, University of Otago, P.O. Box 913, Dunedin, New Zealand. john.mccall@otago.ac.nz.
authors.forename: John L
authors.initials: JL
authors.lastname: McCall
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D000367:Age Factors; D000368:Aged; D003082:Colectomy / Q000009:adverse effects / Q000379:methods / Q000706:statistics & numerical data; D003106:Colon / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods / Q000706:statistics & numerical data; D008198:Lymph Nodes / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D020360:Neoadjuvant Therapy / Q000379:methods; D009367:Neoplasm Staging; D009520:New Zealand / Q000453:epidemiology; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D011878:Radiotherapy / Q000379:methods; D013223:Statistics as Topic