The interaction of lectin-like transcript 1 (LLT1) with CD161 inhibits Natural Killer cell activation. Overexpression of LLT1 contributes to the immunosuppressive properties of tumor cells. However, there are little data about LLT1 expression in human solid tumors. The objective of this paper is to investigate the relationship between LLT1 expression with the clinicopathologic features and its impact on the prognosis of head and neck cutaneous squamous cell carcinoma (cSCC). LLT1 expression was analyzed on paraffin-embedded tissue samples obtained from 100 patients with cSCC by immunohistochemistry. The estimator of Fine and Gray was used to estimate the cumulative incidence curves for relapse. Proportional Hazard models and Hazard ratios (HRs) were used for studying the risk of tumor relapse and mortality. LLT1 strong expression was a significant risk factor for nodal metastasis with crude and adjusted ratios (HRs) of 3.40 (95% CI 1.39-9.28) and 3.25 (95% CI 1.15-9.16); and for cSCC specific death of 6.17 (95% CI 1.79-21.2) and 6.10 (95% CI 1.45-25.7). Strong LLT1 expression is an independent predictor of nodal metastasis and poor disease-specific survival and it might be helpful for risk stratification of patients with cSCC.
Keywords: CLEC2D; Checkpoint; Cutaneous squamous cell carcinoma; Immunohistochemistry; LLT1; Lectin-like transcript 1; Natural killer.