title: Hormone replacement therapy regimens and breast cancer risk(1).
abstract: Hormone replacement therapy (HRT) has increased in the United States over the past 2 decades in response to reports of long-term health benefits. A relationship between HRT and breast cancer risk has been observed in a number of epidemiological studies. In 2002, the Women's Health Initiative Randomized Controlled Trial reported an association between continuous combined HRT and breast cancer risk. The objective of this study was to examine the association between breast cancer risk and HRT according to regimen and duration and recency of use.A multicenter, population-based, case-control study was conducted in five United States metropolitan areas from 1994 to 1998. Analyzed were data from 3823 postmenopausal white and black women (1870 cases and 1953 controls) aged 35-64 years. Odds ratios (ORs) were calculated as estimates of breast cancer risk using standard, unconditional, multivariable logistic regression analysis. Potential confounders were included in the final model if they altered ORs by 10% or more. Two-sided P values for trend were computed from the likelihood ratio statistic. Continuous combined HRT was associated with increased breast cancer risk among current users of 5 or more years (1.54; 95% confidence interval 1.10, 2.17). Additionally, a statistically significant trend indicating increasing breast cancer risk with longer duration of continuous combined HRT was observed among current users (P =.01). There were no positive associations between breast cancer risk and other HRT regimens. Our data suggest a positive association between continuous combined HRT and breast cancer risk among current, longer term users. Progestin administered in an uninterrupted regimen may be a contributing factor. Risk dissipates once use is discontinued.
authors.affiliation: Population Studies and Prevention Program, Karmanos Cancer Institute at Wayne State University, Detroit, Michigan, USA. lw187q@nih.gov
authors.forename: Linda K
authors.initials: LK
authors.lastname: Weiss
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Burkman
authors.forename: Kara L
authors.initials: KL
authors.lastname: Cushing-Haugen
authors.forename: Lynda F
authors.initials: LF
authors.lastname: Voigt
authors.forename: Michael S
authors.initials: MS
authors.lastname: Simon
authors.forename: Janet R
authors.initials: JR
authors.lastname: Daling
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Norman
authors.forename: Leslie
authors.initials: L
authors.lastname: Bernstein
authors.forename: Giske
authors.initials: G
authors.lastname: Ursin
authors.forename: Polly A
authors.initials: PA
authors.lastname: Marchbanks
authors.forename: Brian L
authors.initials: BL
authors.lastname: Strom
authors.forename: Jesse A
authors.initials: JA
authors.lastname: Berlin
authors.forename: Anita L
authors.initials: AL
authors.lastname: Weber
authors.forename: David R
authors.initials: DR
authors.lastname: Doody
authors.forename: Phyllis A
authors.initials: PA
authors.lastname: Wingo
authors.forename: Jill A
authors.initials: JA
authors.lastname: McDonald
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Malone
authors.forename: Suzanne G
authors.initials: SG
authors.lastname: Folger
authors.forename: Robert
authors.initials: R
authors.lastname: Spirtas
mesh_terms: D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D016022:Case-Control Studies; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects* / Q000379:methods*; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D017698:Postmenopause; D015995:Prevalence; D011336:Probability; D011379:Prognosis; D012016:Reference Values; D012307:Risk Factors; D013997:Time Factors; D014481:United States / Q000453:epidemiology