Low number of examined lymph nodes in node-negative breast cancer patients is an adverse prognostic factor

Background: The aim of the study was to determine whether the number of lymph nodes removed at axillary dissection is associated with recurrence and survival in node-negative breast cancer (NNBC) patients. Patients and methods: We retrospectively reviewed the medical records of 1606 women with pathologically node-negative T1-T3 invasive breast cancer. Median follow-up was 61 months (range 2-251). Potential prognostic factors assessed included: number of axillary lymph nodes examined, age, menopausal status, tumor size, histological type, tumor grade, estrogen receptor(ER), progesterone receptor (PR) and HER2. Results: At 5 years, relapse-free survival (RFS) rate was 85% and breast cancer-specific survival (BCSS) rate was 94%. In univariate analysis, factors significantly associated with lower RFS and BCSS were: fewer than six lymph nodes examined (RFS, P = 0.01; BCSS, P = 0.007), tumor size >2 cm, grade III, negative ER or PR. Statistically significant factors for lower RFS and BCSS in multivariate analysis were: fewer than six lymph nodes examined [RFS, hazard ratio (HR) 1.36, P = 0.029; BCSS, HR 1.87, P = 0.005], tumor size >2 cm, tumor grade III and negative PR. Conclusions: Examination of fewer than six lymph nodes is an adverse prognostic factor in NNBC because it could lead to understaging. Six or more nodes need to be examined at axillary dissection to be confident of a node-negative status. This may be useful, in conjunction with other prognostic factors, in the assessment of NNBC patients for adjuvant systemic therapy.