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Study Question: Does the use of post-menopausal vaginal estradiol (VE) affect the mortality risk for coronary heart disease (CHD) and stroke., Summary Answer: The use of VE reduces the risk for cardiovascular mortality., What Is Known Already: A growing number of women use VE for post-menopausal genitourinary symptoms. Although this therapy is intended to have only local effects, estrogen is absorbed into the blood circulation and thus VE use may also have systemic effects., Study Design, Size, Duration: We studied a nationwide cohort in Finland 1994-2009 during which post-menopausal women (n = 195 756) initiated the use of VE (age [mean ± SD] 65.7 ± 10.9 years). Follow-up data gathered 1.4 million women-years and we assessed the mortality risk due to CHD (n= 9656) or stroke (n = 4294)., Participants/materials, Setting, Methods: The mortality risk in VE users was compared with that in the age-matched background population (standardized mortality ratio; [SMR]; 95% confidence interval) and related to various durations of exposure to VE (1 to ≤3, >3 to ≤5, >5 to ≤10 and >10 years)., Main Results and the Role of Chance: The use of VE was accompanied by decreases in the risk for CHD and stroke death. The risk reduction for CHD death was highest for >3 to ≤5 years exposure (SMR 0.64; 0.57-0.70) and for stroke for >5 to ≤10 years exposure (SMR 0.64; 0.57-0.72). The risk reductions for both CHD and stroke mortality were detected in all age groups with the highest risk reduction being in women aged 50-59 years (SMR 0.43; 0.19-0.88 and SMR 0.21; 0.06-0.58, respectively)., Limitations, Reasons for Caution: Our series lack a placebo arm and thus, may harbor a healthy woman bias. Moreover, data on clinical variables such as weight, smoking, blood pressure and family background were unobtainable for this study. Women using both VE and systemic hormone therapy (HT) were included in the comparator background population. This should not cause any significant error because the proportion of women using VE or other HT was modest (<10% in age-matched population) and because the use of systemic HT also reduces death risks in the same population. Our data cannot be directly applied for local regimens containing conjugated equine estrogens, because they are absorbed differently and may show effects that differ from those of estradiol., Wider Implications of the Findings: In 1000 women using VE for up to 10 years, a maximum of 24 fewer CHD deaths and 18 fewer stroke deaths is likely to occur., Study Funding/competing Interests: This work was supported by unrestricted grants from the Päivikki and Sakari Sohlberg Foundation, the Emil Aaltonen Foundation, the Finnish Medical Foundation, Finska Läkaresällskapet, the Orion Farmos Research Foundation, the Paavo Nurmi Foundation and a special governmental grant for health sciences research. The funding sources had no role in the study design, data handling or manuscript preparation. EPID Research is a company that performs financially supported studies for several pharmaceutical companies. Dr Korhonen, Dr Hoti and MSc Vattulainen, employed by Epid Research, report financial activities from several other pharmaceutical companies outside the submitted work. Dr Mikkola has been a speaker and/or received consulting fees from Mylan and Novo Nordisk. Dr Tuomikoski has been a speaker and/or received consulting fees from Orion and Mylan. The remaining authors report no conflict of interest., (© The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The authors conducted a nationwide cohort study to evaluate the association between postmenopausal hormone therapy and meningioma incidence in Finland. All women who had used hormone therapy at least for 6 months at the age of 50 years or older during 1994-2009 were included. Women who had used postmenopausal hormone therapy were identified from the medical reimbursement register of the Social Insurance Institution (131,480 estradiol users and 131,248 estradiol-progestin users), and meningioma cases were identified from the Finnish Cancer Registry. During the average 9 years of follow-up, 289 estradiol users and 196 estradiol-progestin users were diagnosed with meningioma. Ever use of estradiol-only therapy was associated with an increased risk of meningioma (standardized incidence ratio = 1.29, 95% confidence interval: 1.15, 1.44). Among women who had been using estradiol-only therapy for at least 3 years, the incidence of meningioma was 1.40-fold higher (95% confidence interval: 1.18, 1.64; P < 0.001) than in the background population. In contrast, this risk was not increased in users of combination therapy (standardized incidence ratio = 0.93, 95% confidence interval: 0.80, 1.06). There was no difference in risk between continuous and sequential use of hormone therapy. Estradiol-only therapy was accompanied with a slightly increased risk of meningioma.

Objective: To estimate the risk of endometrial cancer in all Finnish postmenopausal women using various forms of estradiol-progestin therapy., Methods: All Finnish women (aged more than 50 years) who had used estradiol-progestin therapy in 1994-2006 for at least 6 months (n=224,015) were identified from the national medical Reimbursement Registry and linked to the Finnish Cancer Registry. A total of 1,364 type I and 38 type II endometrial cancers were recorded by the end of 2006. The incidence of endometrial cancer in estradiol-progestin therapy users was compared with that in the general population in this cohort study., Results: The use of a continuous estradiol-progestin therapy regimen for 3 years or more was associated with a 76% reduction of the risk for type 1 cancer (95% confidence interval [CI] 6-60%). In contrast, the use of a sequential estradiol-progestin therapy regimen for at least 5 years was accompanied with a 69% elevation (95% CI 43-96%) if the progestin was added monthly, and with a significantly higher, 276% risk elevation (95% CI 190-379%) if progestin was added at 3-month intervals. Sequential regimens containing norethisterone acetate, medroxyprogesterone acetate or dydrogesterone administered orally showed no significant differences in the endometrial safety. Oral and transdermal norethisterone acetate were associated with similar risk elevations. Women using a monthly sequential estradiol-progestin regimen tended to be diagnosed with endometrial cancer in an earlier stage than the background population., Conclusion: Use of a continuous rather than a sequential estradiol-progestin regimen decreases the risk of endometrial cancer, whereas the route of administration or type of progestin does not differ in terms of endometrial cancer risk., Level of Evidence: II.

Objective: To evaluate whether the risk of estrogen-only therapy on breast cancer varies by dose, constituent, and route of administration., Methods: All Finnish women older than age 50 years using oral or transdermal estradiol (n=84,729), oral estriol (n=7,941), or vaginal estrogens (n=18,314) for at least 6 months during 1994-2001 were identified from the national medical reimbursement register. They were followed for breast cancer with the aid of the Finnish Cancer Registry to the end of 2002., Results: Altogether, 2,171 women with breast cancer were identified. The standardized incidence ratio of breast cancer with systemic estradiol for less than 5 years was 0.93 (95% confidence interval 0.80-1.04), and for estradiol use for 5 years or more, 1.44 (1.29-1.59). Oral and transdermal estradiol was accompanied by a similar risk of breast cancer. The risk was most prominent with the dose greater than 1.9 mg/d orally; whereas the risk associated with transdermal route was not dose-dependent. The standardized incidence ratio for the lobular type of breast cancer (1.58) was slightly higher than that for the ductal type (1.36). The use of estradiol was associated with both localized breast cancer (1.45; 1.26-1.66) and cancer spread to regional nodes (1.35; 1.09-1.65). The incidence of carcinoma in situ (n=32) was increased (2.43; 1.66-3.42) among estradiol users., Conclusion: Estradiol for 5 years or more, either orally or transdermally, means 2-3 extra cases of breast cancer per 1,000 women who are followed for 10 years. Oral estradiol use for less than 5 years, oral estriol, or vaginal estrogens were not associated with a risk of breast cancer., Level of Evidence: II-2.