Effect of aromatase inhibitors on the lipid profile of postmenopausal breast cancer patients

Abstract

The two most commonly used alternative strategies of endocrine treatment in postmenopausal women with hormone-receptor-positive breast cancers are either the interference with estrogen signaling by a selective estrogen-receptor modulator, such as tamoxifen, or the inhibition of endogenous estrogen production via an aromatase inhibitor (AI). Tamoxifen has been used effectively for over 30 years and it is generally accepted that it exerts a beneficial effect on lipid profiles. Still, its use has been questioned especially in recent years, following indication of an increased risk of endometrial cancer, thromboembolic events and tolerability concerns, along with, most importantly, the development of resistance during long-term adjuvant treatment. On the other hand, inhibition of aromatase, the enzyme that converts androgens to estrogens, with an AI has been shown to be an effective alternative to tamoxifen in multiple clinical trials with anastrozole, letrozole and exemestane. At the same time, due to the high levels of estrogen deprivation caused by AIs, there is uncertainty over the long-term safety of these agents, in particular with respect to the effects on bone metabolism of postmenopausal women and the lipid profile, and thus, cardiovascular disease. Current data on AIs showing favorable, neutral or unfavorable effect on different lipid parameters in various studies, do not allow the drawing of any final conclusions about their effect on lipid metabolism. However, considering disease outcome, particularly in high-risk patients, the benefits of receiving an AI are likely to outweigh the disadvantages of any changes to lipid profiles. Therefore, each patient should be carefully evaluated before the appropriate therapy is decided and blood lipid levels should be monitored during adjuvant hormonal treatment; the instigation of lipid-lowering treatment should be undertaken if required. © 2010 Future Medicine Ltd.