In addition, key genes of DNA repair and immune regulation were analyzed in relation to CCA prognosis, the results of which suggested that DNA repair gene XPC (HR = 0.369, P = 0.048) and immune regulator CD28 (HR = 0.364, P = 0.045) were related with favorable survival of CCA (Table S2). This evidence concerns the gene CD28 and cholangiocarcinoma.