BIRC5 and esophageal squamous cell carcinoma: Among the three subgroups (OCT4-positive/Survivin-positive, OCT4-negative/Survivin-positive, OCT4-negative/Survivin-negative), patients with OCT4-positive/Survivin-positive ESCC had a significantly poorest prognosis (p<0.001), and the longest OS was documented in OCT4-negative/Survivin-negative subgroup (Fig. 2A).