Tumour-infiltrating lymphocytes, programmed death ligand 1 and cyclooxygenase-2 expression in skin melanoma of elderly patients: clinicopathological correlations.

Age is an important prognostic factor in melanoma; notably, elderly patients tend to present with advanced stage skin melanoma (SM) and worse outcome. Moreover, SM is an immunogenic cancer, and its interaction with the aging immune system could have an effect on biologic behaviour of this disease. Tumour-infiltrating lymphocytes (TILs) could represent the host response in SM; it has been shown that higher grade of TILs is associated with better survival. Moreover, programmed death ligand 1 (PD-L1) and cyclooxygenase-2 (COX-2) are potential markers of host immune response and inflammation. We retrospectively reviewed 113 consecutive cases of early-stage SM that occurred in patients aged greater than or equal to 65 years at the time of diagnosis, followed between January 2010 and March 2014 at the University and General Hospital of Udine, Italy. The aim of this study was to evaluate TILs grade, PD-L1 expression on TILs and tumour expression of PD-L1 and COX-2 and their prognostic value in elderly patients with early SM. A better disease-free survival as well as melanoma-specific survival (MSS) was significantly associated with TILs [hazard ratios (HR): 0.41, 95% confidence interval (CI): 0.20-0.84, P=0.02 and HR: 0.37, 95% CI: 0.17-0.82, P=0.01, respectively]. PD-L1 positivity on TILs was associated with a better MSS (HR: 0.41, 95% CI: 0.17-0.97, P=0.04). Moreover, among patients with TILs, those showing COX-2 positivity on tumour cells and no PD-L1 expression on TILs had a worse disease-free survival and MSS (HR: 5.18, 95% CI: 1.33-20.23, P=0.018; HR: 6.21, 95% CI: 1.20-32.24, P=0.03; respectively). Immune and inflammatory markers deserve further investigation in aging patients with melanoma.