Does sentinel lymph node status have prognostic significance in patients with acral lentiginous melanoma?

Background: The prognostic benefit of sentinel lymph node biopsy (SLNB) and factors predictive of survival specifically in patients with acral lentiginous melanoma (ALM) are unknown. Methods: The SEER database was queried for ALM cases that underwent SLNB from 1998 to 2013. Clinicopathological factors were correlated with SLN status, overall survival (OS), and melanoma-specific survival (MSS). Results: Median age for the 753 ALM study patients was 65 years, and 48.2% were male. Median thickness was 2 mm with 38.1% of cases having ulceration. SLN metastases were detected in 194 of 753 cases (25.7%). Multivariable analysis showed that thickness, Clark level IV-V, and ulceration significantly predicted for SLN metastasis (P < 0.05). For patients with positive SLN, 5-year OS and MSS were significantly worse at 48.1% and 58.9%, respectively, compared with 78.7% and 88.5%, respectively, for patients with negative SLN (P < 0.0001). On multivariable analyses, older age, male gender, increasing thickness, ulceration, and a positive SLN significantly predicted for worse OS and MSS (all P < 0.05). Conclusion: This study confirms the important role of SLNB in ALM. SLN metastases are seen in 25.7% of ALM cases, providing significant prognostic information. In addition, thickness, ulceration status, and SLNB status significantly predict survival in patients with ALM.