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Improving access and ensuring the quality of melanoma sentinel node biopsy services

Melanoma incidence is increasing and surgical staging, using sentinel node biopsy (SNB), is increasingly important. SNB facilitates locoregional control and improves 10-year overall survival in intermediate-thickness melanoma presumably by removing lowvolume metastatic disease. Adjuvant systemic therapies are funded in the presence of sentinel node metastases; this therapy reduces risk of recurrence and improves survival. In Australia, SNB is recommended for primary melanomas ≥1 mm Breslow thickness, or ≥0.8 mm with ulceration/ mitoses on histopathology. The chance of positive SNB is approximately 10%, but individual risk can be further stratified using clinical and pathological factors. However, only around 50% of those eligible undergo SNB. Expanding access to SNB through regional centres may improve uptake, particularly for patients unwilling or unable to travel. This is of relevance in the setting of COVID-19, where there are additional hurdles to travel. The recent Provincial Surgeons Australia meeting included a master class on SNB application and technique. For a melanoma SNB to be successful, there must be consideration of techniques in nuclear medicine, surgery and pathology. Maintaining quality remains of utmost importance and quality assurance assessment should be undertaken in surgical oncology programmes. We audited our melanoma SNB practice over a 2-year period, with a median follow-up of 24 months from the date of SNB. We collected demographic, histological, lymphoscintigraphy and recurrence data. This enabled comparison to established oncological quality assurance parameters: the rates of sentinel node identification (at least one sentinel node removed), complete SNB (all identified sentinel nodes removed) and false-negative (FN) SNB (regional node recurrence after negative SNB) (Tables 1,2). Overall, our data were reassuring: a sentinel node was identified in all but one case, and our complete SNB rate was 81.2%. Our incomplete rate was 18.8%, on par with the literature (17.7–40%). Incomplete SNB did not differ by region. The SNB was positive (contained metastatic melanoma) in 10.2% of cases. One patient had an FN SNB, with a calculated FN rate (FN/TP + FN) of 7.1% at 24 months. This is within the spectrum reported (2.8–21%), and within the proposed acceptable calculated FN rate (15%). Our population was somewhat older (63.9 versus 52 years) and had thinner primary melanomas (60% < 2 mm), lower rates of ulceration (19.3%) and microsatellites (0.2%), with fewer head and neck primaries (24.9%) compared to major trials. This explains our lower positive SNB rate and, combined with a shorter follow-up period, our relatively low FN rate which would be expected to increase over time. The number of patients eligible for SNB, combined with difficulty in travel due to distance, cost and, recently, COVID-19 means that there is an imperative to increase availability of SNB to regional centres. This would hopefully increase patients accessing melanoma SNB and adjuvant systemic therapies, thereby improving survival outcomes. For this to have effect, maintaining the robustness of the SNB procedure is essential and we have demonstrated a Table 1 Sample demographics (n = 117)