title: Prognostic significance of the number of positive lymph nodes in women with T1-2N1 breast cancer treated with mastectomy: should patients with 1, 2, and 3 positive lymph nodes be grouped together?
abstract: OBJECTIVE
  To determine whether patients with 1, 2, or 3 positive lymph nodes (LNs) have similar survival outcomes.
  
  
  METHODS
  We analyzed the Surveillance, Epidemiology, and End Results registry of breast cancer patients diagnosed between 1990 and 2003. We identified 10,415 women with T1-2N1M0 breast cancer who were treated with mastectomy with no adjuvant radiation, with at least 10 LNs examined and 6 months of follow-up. The Kaplan-Meier method and log-rank test were used for survival analysis. Multivariate analysis was performed using the Cox proportional hazard model.
  
  
  RESULTS
  Median follow-up was 92 months. Ten-year overall survival (OS) and cause-specific survival (CSS) were progressively worse with increasing number of positive LNs. Survival rates were 70%, 64%, and 60% (OS), and 82%, 76%, and 72% (CSS) for 1, 2, and 3 positive LNs, respectively. Pairwise log-rank test P values were <.001 (1 vs 2 positive LNs), <.001 (1 vs 3 positive LNs), and .002 (2 vs 3 positive LNs). Multivariate analysis showed that number of positive LNs was a significant predictor of OS and CSS. Hazard ratios increased with the number of positive LNs. In addition, age, primary tumor size, grade, estrogen receptor and progesterone receptor status, race, and year of diagnosis were significant prognostic factors.
  
  
  CONCLUSIONS
  Our study suggests that patients with 1, 2, and 3 positive LNs have distinct survival outcomes, with increasing number of positive LNs associated with worse OS and CSS. The conventional grouping of 1-3 positive LNs needs to be reconsidered.
authors.affiliation: Department of Radiation Medicine and Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA. charlottedai@gmail.com
authors.forename: Charlotte
authors.initials: C
authors.lastname: Dai Kubicky
authors.forename: Solange
authors.initials: S
authors.lastname: Mongoue-Tchokote
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000737:chemistry / Q000401:mortality* / Q000473:pathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008408:Mastectomy / Q000401:mortality*; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D011379:Prognosis; D018426:SEER Program; D016019:Survival Analysis; D047368:Tumor Burden; D055815:Young Adult