Sentinel lymph node biopsy in breast cancer patients treated with neoadjuvant chemotherapy

Sentinel lymph node biopsy (SLNB) is a widely used staging method for patients with early breast cancer. Neoadjuvant chemotherapy modifies the anatomical conditions in the breast and axilla, and thus SLNB remains controversial in patients treated preoperatively. The aim of this study was to demonstrate the reliability and accuracy of this procedure in this particular group of patients.

The retrospective study analyzed medical records of patients diagnosed with primary breast cancer between the years 2005 and 2009. Of the patients treated by neoadjuvant therapy, 343 underwent lymphatic mapping to identify sentinel lymph nodes, and these were included in the analysis.

The overall detection rate of sentinel lymph nodes was 80.8%. It was strongly influenced by clinical lymph node status (significantly higher success rate in lymph node-negative patients); higher detection rates were also associated with age <50 years, estrogen receptor positivity, lower proliferation index, and absent lymphovascular space invasion. The false-negative rate was 19.5% and was only marginally significantly dependent on lymphovascular space invasion. The overall accuracy of the method was 91.5%.

By using the present technique, sentinel lymph node biopsy cannot be recommended as a reliable predictor of axillary lymph node status when performed at the authors' institution after neoadjuvant chemotherapy. Infrequent use of blue dye for lymphatic mapping, low number of resected sentinel lymph nodes, and absence of any selection among patients included in the study could be the main factors responsible for the low detection rate and high false-negative rate.