IDO1 and nasopharyngeal carcinoma: Results on prognostic significance of IDO1 expression in other types of cancer are heterogenous: high IDO1 expression was correlated with worse survival in gastrointestinal (Ferdinande et al. 2012; Théate et al. 2015) and gynecologic cancers (Inaba et al. 2009; Théate et al. 2015), nasopharyngeal carcinoma (Ben-Haj-Ayed et al. 2016) and melanoma (Théate et al. 2015), whereas it was correlated with better survival in renal cell carcinoma (Riesenberg et al. 2007) and hepatocellular carcinoma (Ishio et al. 2004).