Sparsity of dendritic cells and cytotoxic T cells in tumor microenvironment may lead to recurrence in basal cell carcinoma.

ABSTRACT

BACKGROUND: Antitumor immune response affects tumor growth. The effect of antitumor immune response on recurrence has been poorly studied in basal cell carcinoma (BCC). OBJECTIVES: To investigate the effects of the peritumoral immune infiltrate on BCC recurrence. METHODS: A total of 30 BCC patients without recurrence and 29 BCC patients with recurrence were included in this retrospective study. Non-recurrent tumor samples as well as primary and recurrent tumor samples from the recurrent group were stained immunohistochemically with anti-CD4, CD8, CD25, FOXP3, CD68, CD163, and CD1a antibodies. Immune infiltrates were semiquantitatively evaluated. RESULTS: BCC tumor microenvironment was rich in CD4+ cells. CD163 expression was higher than CD68. In primary tumors of the recurrent group, CD8 expression was significantly lower than CD4 expression. CD1a expression was lower in primary tumors of the recurrent group than in nonrecurrent tumors. CONCLUSIONS: Our results suggest the existence of an immunosuppressive microenvironment in BCC. Lower CD8+ T-cell numbers and sparsity of dendritic cells in primary tumors of recurrent patients suggest further immunosuppression in the tumor microenvironment and an increase in recurrence risk. This is the first study that evaluates and compares tumor immune microenvironments of primary and recurrent BCC lesions with several markers and investigates the role of antitumor immunity on BCC recurrence.