Table 6

Estimated number of deaths up to the end of the year 2002 in the Million Women Study cohort and minimum and maximum detectable relative risks for certain common conditions

Current versus never users

Current users of 5+ years duration versus never users

Cause of death

Expected number of deaths*

Minimum detectable RR^† > 1

Maximum detectable RR^† < 1

Minimum detectable RR^† > 1

Maximum detectable RR^† < 1

All cancers

12 600

1.06

0.94

1.08

0.92

Colorectal cancer

1200

1.20

0.82

1.25

0.77

Lung cancer

2000

1.15

0.86

1.19

0.82

Breast cancer

2800

1.13

0.88

1.16

0.85

Ovarian cancer

1100

1.20

0.81

1.26

0.76

Endometrial cancer

250

1.41

0.65

1.53

0.56

All circulatory disease

8000

1.08

0.93

1.10

0.91

Ischaemic heart disease

5000

1.09

0.91

1.12

0.88

Stroke

1700

1.16

0.85

1.21

0.81

All causes of death

23 200

1.05

0.95

1.06

0.94

^*Based on national mortality rates for 1996 in England and Wales with the assumption that death rates from causes other than breast cancer are 20% lower than the national rate and that breast cancer death rates are 30% lower than the national rate. ^†Detectable at the 95% significance level with 80% power, assuming that death rates among never users are equivalent to national rates. RR, risk ratio.

The Million Women Study Collaborative Group Breast Cancer Res 1999 1:73   doi:10.1186/bcr16