ISG15 and neoplasm: In addition, Kaplan–Meier analysis on 130 patients with progression-free survival data available, showed that patients with high ISG15 expression in the tumor epithelium had a significantly longer median progression-free survival time (11 months, 95% CI:7.8–14.2 months) than in patients with low ISG15 expression (5 months, 95% CI:3.5–6.5 months), (p < 0.001, Figure 2E).