title: Breast cancer with different prognostic characteristics developing in Danish women using hormone replacement therapy.
abstract: The aim of this study is to investigate the risk of developing prognostic different types of breast cancer in women using hormone replacement therapy (HRT). A total of 10 874 postmenopausal Danish Nurses were followed since 1993. Incident breast cancer cases and histopathological information were retrieved through the National Danish registries. The follow-up ended on 31 December 1999. Breast cancer developed in 244 women, of whom 172 were invasive ductal carcinomas. Compared to never users, current users of HRT had an increased risk of a hormone receptor-positive breast cancer, but a neutral risk of receptor-negative breast cancer, relative risk (RR) 3.29 (95% confidence interval (CI): 2.27-4.77) and RR 0.99 (95% CI: 0.42-2.36), respectively (P for difference=0.013). The risk of being diagnosed with low histological malignancy grade was higher than high malignancy grade with RR 4.13 (95% CI: 2.43-7.01) and RR 2.17 (95% CI: 1.42-3.30), respectively (P=0.063). For breast cancers with other prognostic characteristics, the risk was increased equally for the favourable and non favourable types. Current users of HRT experience a two- to four-fold increased risk of breast cancer with various prognostic characteristics, both the favourable and non favourable types. For receptor status, the risk with HRT was statistically significantly higher for hormone receptor-positive breast cancer compared to receptor-negative breast cancer.
authors.affiliation: Department of Gynaecology and Obstetrics, Juliane Marie Centre, H:S Rigshospitalet, University of Copenhagen, Denmark. c.stahlberg@dadlnet.dk
authors.forename: C
authors.initials: C
authors.lastname: Stahlberg
authors.forename: A T
authors.initials: AT
authors.lastname: Pedersen
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Andersen
authors.forename: N
authors.initials: N
authors.lastname: Keiding
authors.forename: Y A
authors.initials: YA
authors.lastname: Hundrup
authors.forename: E B
authors.initials: EB
authors.lastname: Obel
authors.forename: S
authors.initials: S
authors.lastname: Møller
authors.forename: F
authors.initials: F
authors.lastname: Rank
authors.forename: B
authors.initials: B
authors.lastname: Ottesen
authors.forename: E
authors.initials: E
authors.lastname: Lynge
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D016021:Epidemiologic Studies; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D017698:Postmenopause; D011379:Prognosis; D012042:Registries / Q000706:statistics & numerical data*; D012307:Risk Factors; D016019:Survival Analysis