Fulvestrant treatment is associated with cholesterol plasma level reduction in hormone receptor-positive metastatic breast cancer patients

Fulvestrant is a pure anti-estrogen hormoal agent formally lacking any estrogen-agonist activity. We analyze the effect(s) of fulvestrant treatment on estrogen target systems in hormoe-sensitive advanced breast cancer patients. Patients received a median of five fulvestrant injections (range 3-19). We observed a partial response in one patient, disease stability in 21 and disease progression in 29 patients with a clinical benefit of 43.2% and a median time to progression of 5 [range 3-20] mo. Total cholesterol levels significantly decreased during treatment (219.8 +/- 45.3 vs. 201.4 +/- 42.1 mg/dl; p = 0.0054) together with LDL-cholesterol (129.7 +/- 41.39 vs. 112.3 +/- 37.1 mg/dl; p = 0.018). HDL-cholesterol and triglycerides did not show significant changes. Reduction of total and LDL-cholesterol was independent from last hormoal treatment or treatment duration. All coagulation indices and mean endometrial mucosa thickness value did not vary. Fifty-one patients [median age 65 (range 48-82) y] were enrolled. All patients received previous hormoal treatments, with 90.2% receiving > or =2 courses. Last hormoal treatment was exemestane, letrozole, anastrozole and other in 30-10-7-4/51 patients respectively. Median withdrawal time was 18 d (range 3-1456). Complete fasting lipid blood profile and coagulation indices were assessed before fulvestrant administration, every 3 mo and at discontinuation time. Endometrial mucosa thickness was evaluated before fulvestrant administration and at end-study time. We observed a lipid lowering effect of fulvestrant possibly related to an influence on lipid metabolism by a mechanism in which a role could be played by progesterone receptor.