Clinical Significance of Axillary Microresiduals After Neoadjuvant Chemotherapy in Breast Cancer Patients with Cytologically Proven Metastases

Background  Neoadjuvant chemotherapy (NAC) has been widely accepted for advanced breast cancer patients, and pathological complete remission (pCR) was revealed to be an important prognostic factor. The pCR status of cytologically proven axillary metastases (ALN-pCR) offers a more powerful prognostic predictor than pCR of the main tumor. This study evaluated the clinical significance of residual micrometastases and discusses screening methods after NAC in patients with cytologically proven axillary metastases. Methods  Eighty patients with a diagnosis of cytologically proven axillary metastases received NAC. All dissected lymph nodes were evaluated using multislice sectioning and cytokeratin immunohistochemistry, and categorized into four groups: no metastases (ALN-pCR), and with metastases ≤0.2 mm (ALN-itc), >0.2 mm but ≤2 mm (ALN-mic), and >2 mm (ALN-mac). Disease-free survival (DFS) and overall survival (OS) were calculated by Kaplan–Meier method based on the status of residual metastases. Results  DFS in patients with ALN-pCR and ALN-itc was significantly longer than that with ALN-mic (P = 0.007, P = 0.045, respectively). OS with ALN-pCR was significantly longer than that with ALN-mic (P = 0.004). There was no significant difference in DFS or OS between ALN-mac and ALN-mic. These data showed the clinical significance of microresidual metastases >0.2 mm after NAC in patients with cytologically proven axillary metastases. Conclusions  Using multislice sectioning, screening for ALN-mic after NAC was clinically important, and that for ALN-itc was not clinically essential.