Breast Cancer from Oral and Transdermal Estradiol: A Cohort Study of Finnish Women

PCSK9 inhibitor and atorvastatin reduce cardiac impairment in ovariectomized prediabetic rats via improved mitochondrial function and Ca2+ regulation

Post‐menopausal women have a higher risk of developing cardiometabolic dysfunction. Atorvastatin attenuates dyslipidaemia and cardiac dysfunction but it can have undesirable effects including increased risk of diabetes and myalgia. Currently, the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor efficiently reduces low‐density lipoprotein cholesterol (LDL‐C) levels more effectively than atorvastatin. We have been suggested that PCSK9 inhibitor attenuated cardiometabolic impairment more effectively than atorvastatin in ovariectomized prediabetic rats. Female Wistar rats (n = 48) were fed a normal diet (ND) or high‐fat diet (HFD) for 12 weeks. Then, HFD rats were assigned to a sham‐operated (Sham) or ovariectomized (OVX) group. Six weeks after surgery, the OVX group was subdivided into 4 treatment groups: vehicle (HFOV), atorvastatin (HFOA) (40 mg/kg/day; s.c.), PCSK9 inhibitor (HFOP) (4 mg/kg/day; s.c.) and oestrogen (HFOE₂) (50 µg/kg/day; s.c.) for an additional 3 weeks. Metabolic parameters, cardiac and mitochondrial function, and [Ca²⁺]_i transients were evaluated. All HFD rats became obese‐insulin resistant. HFS rats had significantly impaired left ventricular (LV) function, cardiac mitochondrial function and [Ca²⁺]_i transient dysregulation. Oestrogen deprivation (HFOV) aggravated all of these impairments. Our findings indicated that the atorvastatin, PCSK9 inhibitor and oestrogen shared similar efficacy in the attenuation in cardiometabolic impairment in ovariectomized prediabetic rats.

Estrogen-alone therapy and invasive breast cancer incidence by dose, formulation, and route of delivery: findings from the WHI observational study

OBJECTIVE

Research on the relationships between different hormone therapy doses, formulation and routes of delivery, and subsequent breast cancer incidence has been limited. This study directly compared different estrogen doses, formulations, and route of delivery of estrogen alone among women with a hysterectomy in relation to invasive breast cancer incidence.

METHODS

The Women's Health Initiative Observational Study is a large multicenter prospective cohort study conducted at 40 US sites. Analyses included 26,525 postmenopausal women with a hysterectomy, aged 50 to 79 years, at study entry, recruited between September, 1993 and December, 1998, with annual follow-up through September 12, 2005.

RESULTS

Average follow-up was 8.2 years. For conjugated equine estrogen (CEE) users, no difference was observed between low-dose CEE (<0.625 mg) compared with conventional-dose CEE (0.625 mg) for breast cancer (hazard ratio [HR] 0.99, 95% confidence interval [CI] 0.65, 1.48)]. Compared with conventional-dose CEE, transdermal estrogen was associated with a nonsignificant lower risk of invasive breast cancer (HR 0.75, 95% CI 0.47, 1.19). The low prevalence of transdermal use likely limited power for this comparison, and for a comparison of oral estradiol to conventional-dose CEE (HR 1.20, 95% CI 0.84, 1.39).

CONCLUSION

Our results indicate that invasive breast cancer risk did not differ appreciably in women with a hysterectomy using estrogen-alone when directly comparing different doses, formulations, and routes of delivery to the conventional oral CEE. These findings suggest that the lower breast cancer risk found in the WHI estrogen-alone trial may extend to lower doses of CEE. Additional research is needed to confirm these hypotheses.

Are all estrogens created equal? A review of oral vs. transdermal therapy

BACKGROUND

To compare oral and transdermal delivery systems in domains of lipid effects; cardiovascular, inflammatory, and thrombotic effects; effect on insulin-like growth factor, insulin resistance, and metabolic syndrome; sexual effects; metabolic effects including weight; and effects on target organs bone, breast, and uterus.

METHODS

Review of the literature 1990-2010. Studies selected on basis of applicability, quality of data, and relationship to topic.

RESULTS

Data applicable to the comparisons of oral versus transdermal delivery systems for postmenopausal estrogen therapy were utilized to perform a review and formulate conclusions.

CONCLUSIONS

Significant differences appear to exist between oral and transdermal estrogens in terms of hormonal bioavailability and metabolism, with implications for clinical efficacy, potential side effects, and risk profile of different hormone therapy options, but neither results nor study designs are uniform. Bypassing hepatic metabolism appears to result in more stable serum estradiol levels without supraphysiologic concentrations in the liver. By avoiding first-pass metabolism, transdermal hormone therapy may have less pronounced effects on hepatic protein synthesis, such as inflammatory markers, markers of coagulation and fibrinolysis, and steroid binding proteins, while oral hormone therapy has more pronounced hyper-coagulant effects and increases synthesis of C-reactive protein and fibrinolytic markers. Both oral and transdermal delivery systems have beneficial effects on high-density lipoprotein cholesterol to low-density lipoprotein cholesterol ratios (oral>transdermal), while the transdermal system has more favorable effects on triglycerides. Incidence of metabolic syndrome and weight gain appears to be slightly lower with a transdermal delivery system. Oral estrogen's significant increase in hepatic sex hormone binding globulin production lowers testosterone availability compared with transdermal delivery, with clinically relevant effects on sexual vigor.