Abstract P1-01-33: Sentinel Lymph Node Biopsy in Breast Cancer Patients Treated with Neoadjuvant Chemotherapy

Abstract

Background: sentinel lymph node biopsy (SLNB) as a reliable surrogate for the standard axillary dissection has became a widely used staging method for patients with primary operable breast cancer. Neoadjuvant chemotherapy modifies the anatomical conditions in the breast and axilla and thus SLNB in patients treated with preoperative cytotoxic therapy still remains controversial technique generally not accepted as equivalent to standard axillary dissection. The primary aim of our study was to evaluate success rate for identification and isolation of sentinel node(s) as well as false negative rate of this procedure to declare whether or not SLNB technique is feasible also in patients with preoperative chemotherapy. The secondary aim was to identify factors that can influence the accuracy of this technique. Methods: during the years 2005-2009 were in our institution diagnosed 1719 new patients with primary breast cancer. 465 of them started neoadjuvant chemotherapy in a curative manner with the intend to be followed by surgery. After completion of neoadjuvant chemotherapy was in 343 patients performed lymphatic mapping to be able to identify sentinel lymph node. In all of these subjects the attempt to identify sentinel node(s) was performed followed by standard axillary dissection without regard to the extent of surgery of the breast — this group of patients is analysed in this study. Results: one or more sentinel lymph nodes were successfully dissected in 277 patients — thus reaching success rate of 80,8%. From the remaining 66 patients there were 54 (15,7%) in whom no radioactivity uptake could be detected in axilla. This success rate was strongly influenced by clinical lymph node status (higher success rate in node negative patients); it was also dependent on features of the tumor (more frequent identification rate associated with estrogen receptor positivity, lower proliferation index and absent lympho-vascular space invasion).and on the age of patients (sentinel mode(s) were more often found in patients under the age of 50). One or more sentinel lymph node was positive in 95 cases out of 271 subjects with identified sentinel nodes and at least one non-sentinel node (35,1%). In 53 patients (19,6%) sentinel node(s) were the only positive nodes in axillary basin. In 23 patients sentinel lymph node was negative even in the case of at least one non-sentinel node with detected malignant cells. This results in false negative rate of 19,5%. This false negativity was only marginally significantly different according to lympho-vascular space invasion (higher false negativity occurred in the absence of lymphovascular invasion, p = 0,048). The overall accuracy of SLNB to correctly predict axillary lymph node status is 91,5%, sensitivity is 80,5% and negative predictive value 86,9%. Conclusion: detection rate as well as false negativity rate were in our study higher than corresponding values in patients without neoadjuvant chemotherapy and as such SLNB should not be recommended as surrogate to standard axillary dissection. On contrary we still believe that after necessary modifications of the technique SLNB can become a reliable predictor of axillary lymph node status in properly selected group of patients after preoperative cytotoxic therapy. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-01-33.