CYP7B1 and benign thyroid gland neoplasm: In a cohort of patients with benign thyroid tumors, PTC (low/intermediate and high risk), poorly differentiated (PDTC), and ATC, the patients with more aggressive tumors (high-risk PTC, PDTC, and ATC) showed decreased levels of blood LDL cholesterol and apolipoprotein B associated with an increase in intra-tumor 27-hydroxycholesterol (27-HC) and a decrease in the mitochondrial enzyme 25-hydroxycholesterol 7-alpha-hydroxylase (CYP7B1), which is responsible for 27-HC catabolism.