High level of TILs is an independent predictor of negative sentinel lymph node in women but not in men.

Factors that are most associated with positive lymph node status in melanoma are Breslow thickness and ulceration. However, there are other factors that have been little explored and could help in the identification of "at risk patients" harbouring occult metastasis. The objective of this study was to determine whether intensity of tumour-infiltrating lymphocytes (TILs) in a cohort study (N = 4133) is an independent predictor of sentinel lymph node (SLN) status in patients with primary cutaneous melanoma. Of the patients with cutaneous melanoma who resulted negative for nodal metastasis, 50.7% had moderate/marked TILs versus 27.7% among those patients who resulted positive for nodal metastasis. In the multivariate analysis, controlling for sex, age, mitotic rate, ulceration and Breslow, high levels of TILs in primary invasive melanoma was associated with a lower risk of developing SLN metastasis (OR 0.46; 95% CI 0.23-0.95, p = 0.037). When the analysis was stratified by sex, the protective effect of moderate/marked TIL remained only for women (OR 0.30; 95% CI 0.10-0.93, p = 0.037) but not for men (OR 0.51; 95% CI 0.19-1.34, p = 0.172). Other independent predictors of negative lymph node were low Breslow thickness (≤ 2.0 mm) and low mitotic rate. Besides predicting a negative lymph node response, TILs were also associated with a decreased risk of 10-year mortality among females with positive lymph node. Our findings suggest that high level of TILs is an independent predictor of negative SLN status among women. Further research is warranted to confirm our findings.