Indocyanine green compared with technetium-99m for sentinel lymph node biopsy in breast cancer: the Flouro trial

Background and purpose: Gold standard sentinel lymph node (SLN) mapping for breast cancer involves technetium-99m (99mTc) but has drawbacks. Indocyanine green (ICG) fluorescence allows real-time visualisation of lymphatics and nodes, but routine use is not established. This study compares equivalency of ICG to 99mTc. Methods: Prospective non-inferiority trial of early breast cancer patients undergoing SLN biopsy with ICG and 99mTc (2021-2023). Number of SLNs identified, including metastatic nodes, and rate of failed mapping, were compared. Surgeon reported ease of use was surveyed based on Likert scale from "very easy" to "very difficult" (1-5). Cost-minimisation analysis performed using micro-costing analysis. Clinical trial registration: ACTRN12621001033831. Results: 181 patients enrolled just past the half-way point of this trial (median age 60 years). There were no adverse reactions. Mean number of SLNs identified with ICG and 99mTc was 2.1 (SD 2.05) and 2.2 (SD 2.15), respectively (p= 0.477). There were 13 cases of failed mapping with ICG and 10 with 99mTc (p= 0.487). Metastatic SLNs were identified in 42 of 181 (23.2%) patients, with 56 metastatic SLNs in total, which represented 13.6% of all 413 SLNs removed. ICG identified 53 of 56 (94.6%) metastatic SLNs and 99mTc identified 55 of 56 (98.2%) (p= 0.256). Mean surgeon reported ease for using ICG and 99mTC was 1.6 (SD 1.01) and 1.5 (SD 0.64), respectively (p= 0.39). Technetium-99m cost an additional AU$1492.72 per case but ICG would require >35 cases before breaking even with initial outlay equipment costs. Conclusions: Trial data so far demonstrates that ICG fluorescence is equivalent to 99mTc in terms of number of SLNs identified, including metastatic nodes, rate of failed mapping and ease of use, in addition to being safe.