Sentinel lymph node biopsy (SLNB) in melanoma and breast cancer was first described in the 1970s, when colloidal gold and blue dye were used to identify the lymphatic drainage of melanoma. Later on, radiolabelled colloids would be combined with intraoperative dye detection of SLNB. In 1990, the technique was validated, and 10 years it became the standard of care.
The technique for SLNB currently uses an isotope tracer, a lymphoscintigram, a gamma probe and blue dye, which involves Nuclear Medicine and Surgery. However, Nuclear Medicine is a costly and time consuming procedure and Blue Dye may not always mark the sentinel lymph node.
In this context, Indocyanine Green (ICG) is an acceptable alternative to the Blue Dyes. When the lymph node basin is known, ICG may obviate the need for Nuclear Medicine, Injection of Radioisotope, Lymphoscintigram, and Gamma Probe, bringing advantages to the procedure. A demonstrative video is shown explaining the technique.
The concordance of ICG and Tc99 was studied through a review of 14 studies including 456 patients from 1990 to 2016 for melanoma. Blue dye +/- Tc99 was able to identify 1.94 nodes while the ICG detection rate was 2.11, not statistically significant. When comparing only Tc99 with ICG, there was no difference in the SLN identification rate in melanoma patients. Comparing only blue dyes, ICG was equal to or better than the detection rate for blue dyes. Regarding breast cancer, 1736 patients from 12 studies from 2005 to 2015 showed no significant differences between ICG and Tc99 for SLN detection.
In conclusion, the supporting data for employing ICG for SLN detection in breast and melanoma patients continues to grow. For immediate breast reconstruction procedures, where ICG is already being employed for mastectomy or microsurgical flap evaluation, the cost savings can be even larger. New protocols need to be implemented and ICG may evolve and eventually replace radioactive isotope and blue dye.