CASP4 is a gene involved in encoding a protein involved in immune response and inflammation [29], and studies have shown that decreased expression of CASP4 is associated with poor prognosis in esophageal squamous cell carcinoma [30], but low expression of CASP4 in our prognostic model is more favorable for the survival of PAAD patients. The gene discussed is CASP4; the disease is esophageal squamous cell carcinoma.