Will neoadjuvant chemotherapy affect the lymphatic routes to the sentinel lymph node? Investigation using indocyanine green fluorescence method.

Abstract

164 Background: Neoadjuvant chemotherapy (NAC) is a standard therapy for breast cancer. However, the changes in the lymphatic route to the sentinel lymph node (SLN) before and after NAC are unclear. Indocyanine green (ICG) fluorescence method of SLN biopsy (ICG-SLNB) is useful because of its high identification rate of the SLN and ability to visualize lymphatic routes. Using ICG-SLNB, we compared the lymphatic routes to the SLN (sentinel lymphatic routes) before and after NAC and investigated whether chemotherapy affects the sentinel lymphatic routes. Methods: From October 2010 to April 2012 20 patients received NAC. In 13 cases of clinical node-negative cancer, we performed SLNB before NAC. We recorded the sentinel lymphatic routes before NAC and confirmed the routes at surgery after NAC by using the same method. In 7 cases of clinical node-positive cancer, we recorded the localization of SLN and lymphatic routes by using the ICG fluorescence method before NAC. After NAC, we performed SLNB with axillary dissection and recorded the sentinel lymphatic routes by photography and drawing. Results: Regardless of the presence or absence of lymph node metastasis, the SLN and sentinel lymphatic routes could be detected before and after NAC in all cases. All sentinel lymphatic routes reached the same location of the SLN before and after NAC. In 3 cases, the number of sentinel lymphatic routes had increased after NAC, but the location of the SLN was the same before and after NAC. Other cases showed no changes in the sentinel lymphatic routes. In clinical node-positive cases of pathological complete response, there was no metastasis to the SLN, but there were 2 metastases in the lymph nodes after back-up dissection. Conclusions: ICG fluorescence method provided visual confirmation that the sentinel lymphatic routes were not affected by NAC. This result suggests that SLNB after NAC can be used to safely and positively identify the SLN in clinical node-negative patients. Further investigation would be required to safely perform SLNB after NAC in clinical node-positive patients.