The Loss of Lymph Node Metastases After Neoadjuvant Chemotherapy in Patients With Cytology-proven Axillary Node-positive Primary Breast Cancer

Abstract

Background: Axillary lymph node (LN) dissection after neoadjuvant chemotherapy (NAC) still remains a standard treatment of initially LN-positive primary breast cancer because of the difficulty of assessment of LN status. The aim of this study was to assess the LN status after NAC in initially LN-positive primary breast cancer patients who were assessed as clinically LN-negative after NAC (ycN0) and identify factors associated with loss of LN metastasis.

Patients and methods: The study cohort comprised 279 patients with cytology-proven LN-positivity before NAC. LN status was assessed by ultrasonography. Regional recurrence-free survival and overall survival according to pathologic LN after NAC (ypN) status were assessed in patients with ycN0.

Results: Of the 279 patients, 179 patients (64.2%) had ycN0. High nuclear grade, estrogen receptor-negative (ER^-), and human epidermal growth factor receptor 2-positive (HER2⁺), were significant predictors of ycN0/ypN0 (P < .001, .007, and .046, respectively). Metastases persisted in 1 or 2 LNs for 5 (20.0%) of 25 patients with ER^-/HER2⁺ and for 4 (21.1%) of 19 patients with ER^-/HER2^-, and in 3 or more LNs for 0 (0%) of 25 patients with ER^-/HER2⁺ and for 1 (5.3%) of 19 patients with ER^-/HER2^-. Patients with ER⁺ tumors had more numerous residual LN metastases than those with ER^- tumors (P < .001). Among patients with ycN0, ypN status was not associated with regional recurrence-free survival or overall survival.

Conclusions: Three or more residual LN metastases were rare in patients with ER^- tumors if assessed as ycN0 by ultrasonography. Prospective studies are needed to confirm the prognostic impact of not performing axillary lymph node dissection in such patients.

Keywords: Axillary lymph node metastasis; Pathologic complete response; Ultrasonography.