Compared with those in early stages (FIGO 2018, stages I and II, n = 93), miR-142-5p expression and the ratios of peritumoral IDO+ LVs indicated by both IDO- and D240-positive vessels were significantly higher in advanced stage CSCC patients (FIGO 2018, stages III and IV, n = 23), whereas the number of CD8+ T cells decreased during CSCC progression (Fig. 1a–d). The gene discussed is IDO1; the disease is skin squamous cell carcinoma.