Non-visualized sentinel nodes in breast cancer patients: prevalence, risk factors, and prognosis

Evidence and consensus is lacking in international guidelines regarding axillary treatment recommendations for patients in whom a sentinel lymph node (SLN) cannot be visualized (non-vSLN) during the sentinel node procedure. In this study we aimed to determine the prevalence of non-vSLNs in a Dutch population of breast cancer patients and to examine predictors and survival rate for non-vSLN. A nationwide, retrospective, population-based study was performed including 116,920 patients with invasive breast cancer who underwent a SLN procedure in the Netherlands between January 2005 and December 2013. Of the 76,472 clinically negative patients who underwent a SLN procedure, 1924 patients (2.5%) had a non-vSLN, of whom 1552 (80.7%) underwent an ALND. Multivariate analysis showed predictive factors for non-vSLN: older age (p < 0.001), diagnosis in the period 2005-2009 (p < 0.001), larger tumor size (p = 0.003), and extensive nodal involvement (p < 0.001). Multivariate survival analysis showed a significantly worse survival (HR 1.18, 95% CI 1.03-1.34, p = 0.015) for non-vSLNs patients. However, in the non-vSLN group, an ALND was not statistically significantly associated with a better survival (HR 0.96, 95% CI 0.53-1.75, p = 0.891). Patients with non-vSLNs had less favorable disease characteristics and a worse survival compared to patients with a visualized SLN. Performing an ALND was not associated with a significantly better survival in patients with non-vSLNs. However, further research on the necessity of axillary treatment in this specific patient group is required.