title: Does the axillary lymph node ratio have any added prognostic value over pN staging for South East Asian breast cancer patients?
abstract: BACKGROUND
  Lymph node ratio (LNR, i.e. the ratio of the number of positive nodes to the total number of nodes excised) is reported to be superior to the absolute number of nodes involved (pN stage) in classifying patients at high versus low risk of death following breast cancer. The added prognostic value of LNR over pN in addition to other prognostic factors has never been assessed.
  
  
  METHODS
  All patients diagnosed with lymph node positive, non-metastatic invasive breast cancer at the National University Hospital (Singapore) and University of Malaya Medical Center (Kuala Lumpur) between 1990-2007 were included (n = 1589). Overall survival of the patients was estimated by the Kaplan Meier method for LNR [categorized as low (>0 and <0.2), intermediate (0.2-0.65) and high (>0.65-1)] and pN staging [pN1, pN2 and pN3]. Adjusted overall relative mortality risks associated with LNR and pN were calculated by Cox regression. The added prognostic value of LNR over pN was evaluated by comparing the discriminating capacity (as indicated by the c statistic) of two multivariate models, one including pN and one including LNR.
  
  
  RESULTS
  LNR was superior to pN in categorizing mortality risks for women ≥60 years, those with ER negative or grade 3 tumors. In combination with other factors (i.e. age, treatment, grade, tumor size and receptor status), substituting pN by LNR did not result in better discrimination of women at high versus low risk of death, neither for the entire cohort (c statistic 0.72 [0.70-0.75] and 0.73 [0.71-0.76] respectively for pN versus LNR), nor for the subgroups mentioned above.
  
  
  CONCLUSIONS
  In combination with other prognosticators, substitution of pN by LNR did not provide any added prognostic value for South East Asian breast cancer patients.
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.
authors.forename: Nakul
authors.initials: N
authors.lastname: Saxena
authors.forename: Mikael
authors.initials: M
authors.lastname: Hartman
authors.forename: Cheng-Har
authors.initials: CH
authors.lastname: Yip
authors.forename: Nirmala
authors.initials: N
authors.lastname: Bhoo-Pathy
authors.forename: Lay Wai
authors.initials: LW
authors.lastname: Khin
authors.forename: Nur Aishah
authors.initials: NA
authors.lastname: Taib
authors.forename: Lai-Meng
authors.initials: LM
authors.lastname: Looi
authors.forename: Siew-Eng
authors.initials: SE
authors.lastname: Lim
authors.forename: Soo-Chin
authors.initials: SC
authors.lastname: Lee
authors.forename: Helena M
authors.initials: HM
authors.lastname: Verkooijen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001365:Axilla; D001943:Breast Neoplasms / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D016016:Proportional Hazards Models; D012372:ROC Curve; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D012306:Risk; D012846:Singapore; D055815:Young Adult
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone