261PThe application of indocyanine green fluorescence navigation method to a sentinel lymph node biopsy after neoadjuvant chemotherapy in node-positive breast cancer

Background: Approximately 40% of patients with node positive in axilla (N1) will have axillary pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC). The application of sentinel lymph nodes (SNs) biopsy (SNB) following NAC for initially node-positive breast cancer is unclear because of high false-negative results in previous studies (SENTINA, ACOSOG Z1071). These trials, using blue dye (BD) and/or radioisotope (RI) agent, showed the diagnostic accuracy of SNB was closely related to the number of SNs. We presented the efficacy of indocyanine green (ICG) fluorescence navigation method for SNB in clinically node-negative (cN0) patients (ASCO2008). The fluorescent ICG method can provide higher number of SNs. Moreover, some reports showed that florescence SNs with metastases could not be identified by radioactivity. To determine the detection rate, the false-negative rate of SNs using the fluorescent ICG method after NAC for biopsy-proved N1 breast cancer retrospectively. Methods: Of 2301 patients (January 2010 - March 2018), 135 women with N1 (fine needle aspiration or core needle biopsy proved) received NAC. Node status after NAC was evaluated by ultrasound findings: Group 1 (N1 converted ycN0, n = 105) and Group 2 (N1 remained ycN1, n = 30). All patients underwent SNB using both ICG- and BD-method and axillary lymph node dissection. Results: The average number of SNs removed were Group 1 (ICG: 3.65, BD: 1.37), Group 2 (ICG: 2.99, BD: 0.93). Detection rate of SNs: Group 1 ICG 97.1% (95% CI 91.9-99.0, 102 of 105), BD 77.1% (95% CI 68.2-84.1, 81 of 105), Group 2 ICG 86.7% (95% CI 70.3-94.7, 26 of 30), BD 53.3% (95% CI 36.1-69.8, 16 of 30). Resulting of a false-negative rate: Group 1 ICG 7.69% (95% CI 2.65-20.3, 3 of 39), BD 35.7% (95% CI 20.7-54.2, 10 of 28), Group 2 ICG 11.5% (95% CI 4.00-29.0, 3 of 26), BD 18.8% (95% CI 6.59-43.0, 3 of 16). Axillary pCR was 46.7% (63 of 135). Conclusions: In patients whose axillary nodal status converted from N1 to ycN0, the fluorescent ICG method with higher number detection of SNs showed a remarkable high detection rate and a low false-negative rate of SNs, compared with those of Blue dye which is one of conventional method. Legal entity responsible for the study: The authors. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.