Discussion
breast cancer
ADVERSE REACTIONS, SKIN, FAT NECROSIS, BREAST CANCER
SLN biopsy with BD-RI has become a diagnostic standard of care in clinically node-negative, early breast cancer within the past two decades.Blue dye was replaced with ICG in this study after a decade of its use. The outcomes of this transition demonstrate equivalency between the two dual techniques in terms of number of SLNs identified, rate of failed mapping, and identification of metastatic SLNs. The abandonment of BD in favour for ICG has not only been justified in terms of SLN biopsy efficacy, but so far has been safe with no adverse reactions associated with ICG. These results could aid surgeons that use BD in considering an alternative tracer with the caveat being higher costs.The SLN detection rates were equivalent for both ICG-RI and BD-RI. There were no cases of failed mapping with either dual technique. The overall node positivity rate was similar between the two techniques. There is a paucity of data on this new approach with ICG-RI; one study used this combination in a small series (32 patients) and reported a SLN detection rate of 100%. The study also added BD to the ICG-RI technique and did not compare it to the “gold standard”.There were initial concerns with ICG fluorescence detecting higher nodal counts between three to five per patient in early studies. This is thought to be related to the low molecular weight and fast diffusion of ICG through lymphatics.The importance of BD use as a tracer for SLN biopsy has come under scrutiny since the introduction of RI and more recently, ICG. Skin tattooing and skin or fat necrosis at site of injection are well described.Understanding the learning curve of a new surgical technique is important in considering its adoption. No trials, to date, have evaluated the learning curve of SLN biopsy with ICG. Surgeons require approximately 40 cases for SLN biopsy proficiency as described in the ALMANAC trial using “gold standard,” dual technique.The costs involved with a new technology compared to current “gold standard” is a key consideration in its adoption. Fluorescence imaging requires additional expenditure, including costs of ICG drug and the dedicated camera. This study found that tracer combination of ICG-RI was more expensive than BD-RI. Although there were significant costs associated with adverse reactions from BD, the initial capital outlay costs of ICG were significantly higher. These costs associated with ICG may not be worthwhile to prevent such a low rate of adverse reactions related to BD. The adoption of ICG-RI may pose financial challenges due to its higher initial outlay costs as well as the recurrent cost of ICG drug. These cost considerations should be taken into account when considering the feasibility of implementing ICG-RI in real-world, clinical practice. Increased uptake of fluorescence technology could potentially lower costs of the imaging system, which is a significant limiting factor in its adoption. ICG fluorescence as a single technique would, in theory, be less expensive than BD-RI. Use of RI has additional costs from hospital infrastructure to accommodate radioactive materials, specialist staff for lymphoscintigraphy, and patient travel.This study is limited in that it was nonrandomised and lacked a direct comparison to “gold standard” technique, which weakens the strength of the conclusions that can be drawn. No trials to date have compared ICG alone with the “gold standard” dual technique. This is likely due to ICG being a relatively novel technique with the safer option to combine it with another tracer to minimise risk of missing metastatic SLNs. The novel combination of ICG-RI could represent a transition phase with ICG used as a sole tracer in future.This study provides data supporting efficacy of novel dual technique, ICG-RI, for SLN biopsy in early breast cancer with comparable detection rates to the “gold standard” dual technique. Widespread abandonment of RI in the near future is unlikely given its well-established data. Using ICG as an adjunct to RI would be a more pragmatic approach to consider. It can be complementary to RI in the absence of BD. Novel tracer combination, ICG-RI, provided an effective and safe alternative to “gold standard” dual tracer. The caveat was the significantly greater costs associated with ICG.