Abstract

Research Question: Is there a significant difference in cumulative serum lipid events between nonsteroidal and steroidal aromatase inhibitors (AIs) in hormone-sensitive postmenopausal early stage breast cancer?

Background: Studies estimating the effect of AIs in post-menopausal early breast cancer have demonstrated conflicting results regarding the net changes in the composition of lipid profiles. To date, few studies have directly compared the effects of nonsteroidal and steroidal AIs on lipid metabolism.

Design: Lipidemic profile changes were studied in 34 post-menopausal patients randomized to receive either nonsteroidal AIs (n=18) or steroidal AI (n=16). Total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglyceride (TG) levels were measured at baseline and every 3, 6, and 12 months thereafter. The primary endpoint was cumulative incidence of serum lipid events.

Results: The cumulative incidence of serum lipid events at 12 months in the non-steroidal and steroidal arms was 66.67% and 68.75% respectively. The factors associated with serum lipid event were analyzed using univariate and multivariate analyses. In both analyses, LDL-C (HR-1.04, 95% 1.01-1.07; p-0.001) and TC were significantly associated with serum lipid event. There was no significant difference in the cumulative incidence of serum lipid events in either arm (HR, 0.69 95% 0.22-2.17; p-0.522).

Conclusion: Among post-menopausal hormone sensitive early breast cancer, no significant difference in cumulative serum lipid events at 1 year was observed in the steroidal or non-steroidal treatment arms. Importantly, the present study adds to the existing data that AIs significantly alter the mean TC, LDL, and HDL levels over time. Clinical trials investigating these changes in lipid profile and their impact on cardiovascular morbidity should be pursued.