The effect of tamoxifen therapy on serum apolipoprotein A-I level is modified by the apolipoprotein E phenotype

Effects of hormonal treatment on lipids in patients with cancer

Patients with malignant disease may need hormonal therapy as primary or adjuvant treatment or for palliation. Oestrogens usually decrease serum levels of total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), increase high density lipoprotein cholesterol (HDL-C) concentration, but induce an elevation in serum triglyceride (TG) levels. Progestogens in the short-term decrease TC, LDL-C and HDL-C concentrations, and increase TG levels. In long-term treatment, progestogens usually have a small impact on lipid profile. Tamoxifen induces a decrease in TC and LDL-C levels, an increase in TG concentration, whereas either an increase, decrease or no change has been reported for HDL-C levels. Aromatase inhibitors induce an elevation, reduction or no change in lipid variables. These results depend mainly on the trial design, i.e. whether patients received prior treatment with tamoxifen or not and the duration of therapy. Gonadorelin analogues increase all lipid variables, but LDL-C alterations are usually non-significant. Anti-androgens usually decrease TC, LDL-C and HDL-C levels, whereas TG alterations vary. Information regarding the effects on lipid profile of somatostatin analogues is available almost exclusively in patients with acromegaly. In these patients somatostatin analogues usually induce no change or a decrease in TC and LDL-C levels, whereas they increase HDL-C and decrease TG serum concentrations. Oncologists should consider the lifestyle changes, and if needed hypolipidemic treatment, used to lower cardiovascular risk in non-cancer patients. Tamoxifen may rarely cause serious TG-related side effects, like acute pancreatitis.

The effect of apolipoprotein E polymorphism on the response to lipid-lowering treatment with atorvastatin or fenofibrate

Although the effect of apolipoprotein E gene polymorphism on the response to treatment with statins has been studied, the results are conflicting. Moreover, little is known about the possible effect of apolipoprotein E alleles on the response to treatment with fibrates. The purpose of this study was to evaluate the effect of apolipoprotein E polymorphism on lipid-lowering response to treatment with atorvastatin and fenofibrate in patients with different types of dyslipidemia. The study population included 136 patients with heterozygous familial hypercholesterolemia (type IIA dyslipidemia) treated with atorvastatin (20 mg/day) and 136 patients with either primary hypertriglyceridemia (type IV dyslipidemia) or mixed hyperlipidemia (type IIB dyslipidemia) treated with micronized fenofibrate (200 mg/day). Overall, no significant associations were detected between apolipoprotein E genotype and response to treatment with atorvastatin. In patients treated with fenofibrate, significant associations were noted between apolipoprotein E genotype and changes in apolipoprotein B, apolipoprotein E and triglyceride levels. Specifically, in apolipoprotein E2, apolipoprotein E3, and apolipoprotein E4 individuals, apolipoprotein B reductions were 22%, 17%, and 8%, respectively (P = .003); apolipoprotein E reductions were 45%, 20%, and 15%, respectively (P = .006); whereas triglyceride reductions reached 53%, 36%, and 33%, respectively (P = .033). In conclusion, apolipoprotein E genotype had no significant effect on the response to treatment with atorvastatin in patients with heterozygous familial hypercholesterolemia, but in patients with primary hypertriglyceridemia or mixed hyperlipidemia, there was a clear association between apolipoprotein E genotype and response to treatment with fenofibrate.

Cardiovascular Health and Aromatase Inhibitors

Cardiovascular disease is the most frequent cause of death in North American women, and so death resulting from cardiovascular disease, rather than from malignancy, is not uncommon in breast cancer patients. This may be a consequence of the shared risk factors for developing breast cancer and cardiovascular disease, as well as the difficulty of managing cancer patients at higher risk for developing cardiovascular disease. Recently, much attention has focused on understanding the cardiovascular risk factors associated with breast cancer therapies. Tamoxifen has a lowering effect on serum lipids and is reported to decrease the risk of myocardial infarction but to increase the risk of thromboembolic events. Current data indicate that aromatase inhibitors (AIs) are not associated with an increased risk of thromboembolic or cerebrovascular events. Reports of a greater incidence of hypercholesterolaemia when AIs are compared head-to-head with tamoxifen may be a result of the intrinsic lipid-lowering effects of tamoxifen therapy and may be confounded by differences in data collection among trials. The incidence of cardiovascular events associated with AIs in large trials has been reported to be higher in trials comparing AIs with tamoxifen; comparisons within the MA.17 trial, which evaluated an AI versus placebo, did not show increases in hypercholesterolaemia or in cardiovascular events with the AI. When treating breast cancer patients, oncologists should consider the same positive lifestyle changes that are proposed to lower the risk of cardiovascular disease in patients who do not have breast cancer. Moreover, physicians should assess cardiovascular risk, and monitor and treat patients already diagnosed with or at risk for coronary heart disease, according to established guidelines.

Apolipoprotein E and renal disease

Apolipoprotein E (ApoE) is a major constituent of plasma lipoproteins with many biological actions of great significance. Beyond the known influence of ApoE polymorphisms on serum lipid profile, the pathogenesis of atherosclerosis, and the development of neurodegenerative disorders, ApoE also has a major role in the pathogenesis and progression of a variety of renal diseases, as well as in the atherosclerotic complications associated with them. Briefly, the polymorphisms of ApoE are major determinants of plasma lipid levels in uremic patients. They may affect the risk for cardiovascular disease in this population, predispose to the development of diabetic nephropathy, influence the severity of certain glomerulopathies, and regulate mesangial and glomerular functions locally in the kidney microenvironment. Finally, certain mutations of the ApoE gene are associated with a recently described nephropathy, termed lipoprotein glomerulopathy.