Patients with NPC and NPB show elevated levels of both 7-OC (NPC, 72.5–135.5 ng/mL; NPB 65.5–112.5 ng/mL, Fig. 5A) and 7β-HC (NPC, 29.5–69 ng/mL; NPB, 19–54 ng/mL, Fig. 3A) in plasma compared to controls and carrier (7-OC, <8.5 ng/mL; 7β-HC, <2 ng/mL). Here, NPB is linked to nasopharyngeal carcinoma.