The mRNA expression levels of CDC20 were acquired and investigated from TCGA database to identify the differential expression patterns between normal tissues and tumor tissues, finding that in a majority of tumor tissues, the expression of CDC20 was higher than its corresponding normal adjacent tissues, such as Bermuda Laser Class Association (BLCA), breast cancer gene (BRCA), cholangiocarcinoma (CHOL), chronic obstructive airway disease (COAD), and Emergency Services Coordinating Agency (ESCA) (P < 0.05). The gene discussed is CDC20; the disease is cholangiocarcinoma.