Tumor-Infiltrating Lymphocytes in Patients with Melanoma: Which Is Its Prognostic Value?

Oncological impact of tumor-infiltrating lymphocytes (TILs) in melanoma remains controversial. We aimed to determine the significance of TILs on melanoma-specific survival (MSS), recurrence-free survival (RFS), and sentinel lymph node status (SLN). A retrospective analysis of patients undergoing melanoma resection during the period 2009-2019 was performed. Using the Melanoma Institute Australia grading system for TILs, the cohort was divided into two groups: group 1 (G1), patients with TILs grades 1, 2, or 3 and Group 2 (G2), patients with TILs grade 0. From a total of 386 melanoma resections, 151 (39%) were included in G1 and 39 (10%) in G2. Among the 151 patients who underwent SLN biopsy, the positivity rate according to the TILs grades 0, 1, 2, and 3 was 32%, 18%, 14%, and 0%, respectively, p  = 0.02. With an average follow-up of 48 months, the 5-year MSS (G1: 86% vs G2: 75%, p  = 0.002) and the 5-year RFS (G1: 81% vs G2: 60%, p  = 0.004) were significantly higher in G1 than G2. Tumor-infiltrating lymphocytes in melanoma are associated with the SLN status and with a better MSS and RFS.