CYP27A1 and nasopharyngeal carcinoma: The further CYP27A1 metabolite, 3β,7β-diHCA, is a normal constituent of plasma from healthy individuals (control and carriers, 3–5 ng/mL), but is greatly elevated in NPC (40.5–229 ng/mL) and NPB (97–174 ng/mL) plasma and to a lesser extent in LALD (11–52.5 ng/mL) plasma (Fig. 3D).