Million women study: Breast ca and HRT

Question 1

Million women study: Breast ca and HRT

Answer 1

Banks et al
2003
Retrospective cohort study

N = 1,084,110

Mean age 56yo

Aim: investigate relationship between HRT and breast cancer incidence and mortality

50-64yo invited to provide info re: HRT use and routine screening (mammogram, questionnaires etc

Question 2

Primary outcome: Million women study: Breast ca and HRT

Answer 2

-Breast CA from HRT – incidence and mortality

• Incidence INC in current HRT users [RR 1.66], with no INC in past or never users
• Mortality INC [RR 1.22]
• INC greater in E+P [RR 2] > tibolone [RR 1.48] > E alone [RR 1.3]
• INC with INC duration of use
• Risk greater with E implant [RR 1.65] > PO [RR 1.32] > transdermal [RR 1.24]

Question 3

Conclusion- Million women study: Breast ca and HRT

Answer 3

Found 10 yrs combined HRT INC 19 extra breast CA/1,000 women-yrs with E+P, and 5 extra breast CA with E only

So current users of HRT at greater risk of incident and fatal breast CA – effect substantially INC for E+P combos, INC duration