The potential impact of modern treatments for breast cancer on bone health

Abstract

The menopause results in certain metabolic changes that contribute to the metabolic syndrome. Loss of estrogen results in an increase in total and low-density lipoprotein (LDL) cholesterol and triglycerides and a decrease in HDL cholesterol. While there is no immediate change in glucose tolerance or blood insulin levels, there is a decrease in pancreatic insulin secretion and a decrease in circulating insulin elimination. With time after menopause, there is a gradual increase in insulin resistance. Weight tends to increase after menopause, and there is a redistribution of body fat, with relative increases in android fat (central abdomen) and decreases in gynoid fat (around the hips and thighs). While there is no obvious immediate increase in blood pressure, the incidence of essential hypertension is increased in postmenopausal women. All these disturbances result in an increased risk for coronary heart disease, which is rare before the menopause but increases in incidence thereafter. Furthermore, the incidence of noninsulin-dependent diabetes mellitus also increases quite dramatically following menopause. Estrogen replacement, as part of hormone replacement therapy (HRT), reverses many of these changes. Thus, there is an improvement in insulin secretion and a reduction in insulin resistance, an increase in HDL cholesterol and a reduction in LDL cholesterol. Triglycerides may increase with oral estrogen but decrease with transdermal estradiol. The addition of a progestogen may modify some of these changes, depending in part on the androgenicity of the steroid. Blood pressure may be reduced with some HRT and central body fat increases are diminished or reversed. An HRT regimen to correct any specific features of the metabolic syndrome can be tailored to the individual, with the judicial use of appropriate doses and types of steroids and routes of administration. When given correctly, HRT can reduce the incidence of CHD and of diabetes mellitus. Management of the metabolic syndrome usually requires dietary intervention to achieve weight loss and improve insulin resistance and dyslipidaemia. A diet with low glycaemic index foods, low fat and adequate protein is essential. However, it should be remembered that insulin resistance can occasionally occur in individuals who are not overweight or obese. The presence of the metabolic syndrome may also require additional medications, such as insulin sensitizers for insulin resistance, lipid-lowering agents for dyslipidaemia and antihypertensive agents for hypertension. This management is probably best left to the specialist.