Table 1 Odds ratios per year of use (OR1s) of oestrogen–progestin therapy and breast cancer risk

From: An overview of menopausal oestrogen–progestin hormone therapy and breast cancer risk

Study

Case users

OR 1 (95% CI)

 

Randomised trial

   

 WHI1 (2003)a

199

1.080 (1.004, 1.167)

 

Prospective studies

   

 Stahlberg2 (2004)a,b

95

1.097 (1.068, 1.127)

 

 MWS3 (2003)a,c

1891

1.077 (1.071, 1.084)

 

 Porch4 (2002)a,b,c

164

1.052 (1.022, 1.084)

 

 Schairer5 (2000)a,d

75

1.060 (0.998, 1.150)

 

Case–control studies

   

 Kirsh6 (2002)b,c

43

1.15 (1.01, 1.33)

 

 Newcomb7 (2002)c

215

1.04 (1.01, 1.08)

 

 Weiss8 (2002)

195

1.065 (1.019, 1.114)

 

 Ross9 (2000)b

425

1.044 (1.014, 1.077)

 

 Magnusson10 (1999)b

399

1.104 (1.073, 1.136)

 

Pooled studies

   

 CGHFBC11 (1997)a,e

194

1.058 (0.996, 1.124)

 

Summary

 

Pooled estimate

 

 All studies

 

1.076 (1.070, 1.082)

Phet=0.074

 US studies1, 4−9,11

 

1.052 (1.036, 1.068)

Phet=0.87

 European studies2,3,10

 

1.079 (1.073, 1.085)

Phet=0.12

 Scandinavian studies2,10

 

1.089 (1.065, 1.114)

Phet=0.32

  1. Abbreviations: CI=confidence interval; OR=odds ratio; WHI=Women's Health Initiative; MWS=Million Women Study; CGHFBC=Collaborative Group on Hormonal Risk Factors in Breast Cancer.
  2. aRisk is based on current and/or recent use rather than total use.
  3. bResults included (or did not specifically exclude) in situ breast cancer cases.
  4. cResults included (or did not specifically exclude) women with unknown age at menopause due to simple hysterectomy.
  5. dCalculated number of cases for women with known age at menopause: 80% of the total number of cases (n=93).
  6. eIncludes mostly US studies.
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