CYP27A1 and cancer: This oxysterol is synthesized through the action of the CYP27A1 enzyme and is present at high levels in the circulatory system.219 Oxysterol has been shown to modulate the TME by recruiting immunosuppressive neutrophils to the metastatic niche, facilitating cancer progression.220 However, some studies have reported conflicting findings regarding the effects of high serum cholesterol levels on cancer progression.