Predictive Factors for Non-sentinel Nodal Metastasis in Patients With Sentinel Lymph Node-positive Breast Cancer

BACKGROUND: Axillary dissection is routinely conducted for all patients with sentinel node (SN)-positive breast cancer. Metastasis to non SNs is not often found after axillary dissection in patients with SN-positive breast cancer. Thus, we investigated clinicopathological features, including immune cells in peripheral blood, in order to identify factors related to metastasis to non-SNs. PATIENTS AND METHODS: We retrospectively investigated 184 patients with SN-positive disease, treated at our institution during the 2013 through 2018 period. All clinicopathological data were obtained before and during surgery. RESULTS: Metastasis to non SNs was observed in 64 cases (35%). The platelet-to-lymphocyte ratio (PLR) and the number of SN metastases were independent of metastasis to non SNs (p=0.023 and p=0.017, respectively). Patients with metastasis to non SNs had significantly lower PLR and more SN metastases. High lymphocyte number and low platelet number resulted in a low PLR. CONCLUSION: PLR might be a marker of metastasis to non SNs.