PDGFA and cholangiocarcinoma: Subsequent Cox regression analysis indicated that high PDGFA expression was an independent factor to predict unfavorable prognosis, which coincided with the results from a few clinical studies about other kinds of tumors, such as osteosarcoma,[20] nephroblastoma,[21] cholangiocarcinoma,[17] gastric cancer,[18] oral squamous cell carcinoma,[9] and neuroblastoma.[19] Collectively, our investigations suggested that overexpression of PDGFA probably could be used as a prognostic biomarker for ESCC patients.