Hormone therapy and ovarian borderline tumors: a national cohort study
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Little is known about the influence of postmenopausal hormone therapy on the risk of ovarian borderline tumors. We aimed at assessing the influence of different hormone therapies on this risk.
A total of 909,875 Danish women 50–79 years old without previous hormone-sensitive cancers or bilateral oophorectomy were followed in this nationwide cohort study 1995–2005. The National Register of Medicinal Product Statistics provided exposure information on all women who redeemed prescriptions on hormone therapy. The National Cancer and Pathology Register provided data on borderline ovarian tumors. Information on confounding factors was available from other national registers. Poisson regression analyses provided risk estimates with hormone exposures as time-dependent covariates.
In an average of 8.0 years of follow-up, 703 incident ovarian borderline tumors were detected. Compared with never users, hormone use for more than 4 years increased the risk of borderline tumors: relative risk (RR) 1.40; 95% confidence interval (CI), 1.09–1.81. Combined estrogen and progestin therapy for more than 4 years increased the risk: RR 1.49 (1.10–2.01), with no difference between cyclic and continuous combined therapy (p = 0.83); RR 1.56 (1.08–2.25) and 1.45 (0.87–2.43), respectively. The RR with estrogen therapy did not differ significantly from RR with combined therapy (p = 0.58): RR 1.27 (0.82–1.98). Disregarding the type of hormone therapy, hormone use for 4 years or less did not increase the risk of borderline tumors.
Combined hormone therapy for more than 4 years increases the risk of ovarian borderline tumors.
KeywordsOvarian borderline tumors Hormone therapy Hormone regimens And duration of hormone use
Postmenopausal hormone therapy
Danish Sex Hormone Register Study
Anatomical therapeutical chemical code
Defined daily doses
This study was supported by grant from the Danish Cancer Society. The Danish Cancer Society had no role in the design or conduct of the study.
Conflict of interest
The authors Mørch, Løkkegaard, Andreasen, and Kjær have no conflicts of interest. Lidegaard has received grants from Schering AG, Berlin, for cover of research expenses and has received fees for speeches on pharmacoepidemiological issues from Schering Denmark and Novo Nordisk.
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