In terms of bilirubin’s effects on immune cells, a 2017 study showed (139) that unconjugated bilirubin upregulates CD39 and thus inhibits Th17 immunoreactivity, this promotes several cancers, such as breast, colorectal, and ovarian cancers (140–142), and thus, the inhibition of TH17 by unconjugated bilirubin can play a role in inhibiting related cancer effects. This evidence concerns the gene ENTPD1 and cancer.