[Predictive value of sentinel lymph node biopsy in prognosis of acral melanoma]

Objective: To explore the application of sentinel lymph node biopsy (SLNB) and its prognostic value in the treatment of acral melanoma. Methods: We retrospective analyzed 118 patients who underwent sentinel lymph node biopsy from Mar 2012 to Jun 2019 with effective follow-up data available in our institute. We ruled out palpable regional lymph node metastasis with preoperative imaging of MRI and ultrasonography, used the (99)Tc(m)-Dextran (Dx) as a tracer, with intraoperative γ-ray probe positioning for SLN capture. Wide resection and reconstruction in primary lesion followed by complete lymph node dissection were underwent SLN positive patients. Cox regression model were used to analyze the prognostic factors. Results: The patients had an average disease history of 53.6 months (2-360 months), the primary lesion located at hands and feet in 84 cases, while 27 cases were subungual and 7 cases were cutaneous. The mean Breslow depth was 3.6 mm, and 72 cases (61.0%) combined with ulceration. The average number of SLN was 2.8, the SLN positive rate was 24.6% (29/118), and the false-negative rate was 2.5% (3/118). There were 24 cases (20.3%) developed clinically positive metastasis, including 7 cases displayed distant metastasis combined with lymph node metastasis (5.9%), 8 cases with clinically positive lymph node metastasis alone (6.8%), and 9 cases with distant metastasis (7.6%). There were 33 patients in stage Ⅰ, 56 patients in stage Ⅱ and 29 patients in stage Ⅲ, with a 5-years overall survival rate of 69.5%. The Breslow depth is an independent risk factor of SLN positive. While Breslow depth, SLN status, SLN positive number and clinically detectable metastasis are independent prognostic factors of the overall survival (P<0.05). Conclusions: Patients without clinically positive regional lymph node metastasis under imaging and physical examinations, SLNB can provide accurate pathologic staging and play an accurate prediction role in the prognostic evaluation. SLNB should be carried out routinely in clinical practice.