Predictors of non-sentinel lymph node metastasis in breast cancer patients with positive sentinel lymph node : pilot study

Background: Sentinel Lymph Node Biopsy (SLNB) procedure was found to be an accurate method of staging the axilla in patients with early stage breast cancer. The standard of care for breast cancer patients with positive SLN metastasis includes complete Axillary Lymph Node Dissection (ALND). However, in 40–70 % of patients, the SLN is the only involved axillary node. Factors predicting non SLN metastasis should be identified in order to define subgroups of patients with positive SLN in whom the axilla may be staged by SLNB alone. Objectives : to identify the factors predicting metastatic involvement of the non-SLNs in breast cancer patients having SLN metastasis. Patients and Methods : data were collected and analyzed from 80 patients with early stage invasive breast cancer (T1, T2, N0, M0) who underwent SLNB at the Surgical Oncology Department, Kuwait Cancer Control Center (KCCC) between November 2004 and February 2009. SLNB was performed using a combined technique (radioactive colloid, and blue dye) in the majority of cases. In some cases, only one technique was used. Complete ALND was performed in the case of failure of SLN identification and in patients with positive SLN. Multiple variables (patient, tumor, and SLN characteristics) were tested as possible predictors of no sentinel lymph node metastasis. Results : the mean age of patients at diagnosis was 46.6 years. The median tumor size was 2 cm. The SLN identification rate was 96.2% (77 out of 80 patients). The SLN was positive in 24 patients (31 %), and half of these showed evidence of capsular invasion. The median number of SLNs removed was two. The median number of positive SLNs was one. The incidence of non-SLN metastasis associated with positive SLN was 50% (12 out of 24 patients). Lymph vascular invasion was found to be the only factor associated with non-SLN metastases. In addition, two trends were observed, though they did not reach the statistical significance: the first is that the majority of patients having capsular invasion of the SLN (8 out of 12 patients, 67 %) had positive non-SLN metastasis, and the second is that the patients having more than one SLN metastasis were more likely to have non-SLN metastasis (4 out of 5, 80 %). Conclusion : in the current pilot study, only the lymph vascular invasion in the area of the primary tumor was found to be significantly related to the no sentinel lymph node metastasis. There was a tendency toward higher incidence of no sentinel lymph node metasta