Do patients with thin melanomas benefit from sentinel lymph node biopsy with selective lymph node dissection?

Abstract

e19061 Background: Sentinel lymph node (SLN) biopsy for thin melanoma remains controversial. While most patients diagnosed with thin melanoma have an excellent prognosis, ~5% will die of their disease. With the growing number of thin melanomas, nearly 25% of all melanoma-related deaths now result from thin primary tumors. Yet these patients are unlikely to have LN disease at presentation and when SLN disease is identified, it is often minimal. It remains unclear whether SLN biopsy with selective LN dissection (LND) represents an opportunity to cure patients with high-risk thin melanoma or whether they are a subgroup with disease likely confined to the SLN(s) or of unclear clinical significance. We undertook this study to examine outcomes in patients with thin melanomas (<1.0mm on biopsy) who underwent SLN biopsy. Methods: From our Melanoma Registry, we identified 338 consecutive thin melanoma cases in 300 patients. Data were verified by pathology and record review. Median patient follow up was 61 months. SAS software was used for statistical analysis. Results: 36 of 300 patients (12%) underwent SLN biopsy. Patients selected for SLN biopsy were younger (median 58 v 69 yrs, p=0.03), their melanomas were thicker (median 0.9 v 0.25 mm), more often level IV/V (44 v 5%), ulcerated (11 v 0.3%) and 53 v 22% had ≥1 mitoses/mm2, all p<0.001. Two (5.5%) were SLN+, one with isolated tumor cells in a solitary SLN, the other with 2.0 and 0.2 mm foci in 2 of 2 SLNs. Neither had additional disease identified after LND. Recurrent disease developed in 6/36 SLN patients (16.7%) and in 20/264 non-SLN patients (6.6%), after a median 32 of months. Isolated regional recurrence as site of first relapse occurred in 9/264 non-SLN patients (3.4%) and in no patients after SLN biopsy, p<0.001. Disease-free and overall survival were governed by tumor thickness. Conclusions: SLN biopsy with selective LND provides excellent regional control and prognostic information for selected patients with thin cutaneous melanoma, and may alter treatment and improve outcome for patients who harbor LN disease. Pending ongoing randomized controlled trial results, selective completion LND for patients with thin melanoma and evidence of SLN metastases appears warranted.