Besides several serum tumor markers such as carcinoembryonic antigen (CEA), squamous cell cancer antigen (SCCA), and tissue polypeptide antigen (TPA) being used as serum tumor markers clinically, we recently reported that serum elafin can serve as another potential prognostic marker in ESCC patients with stage I–IIIA tumors [4,5,6]. The gene discussed is PI3; the disease is esophageal squamous cell carcinoma.