Decrease in breast cancer incidence following a rapid fall in use of hormone replacement therapy in Australia.
Date
2008
Authors
Canfell, Karen
Banks, Emily
Moa, Aye M
Beral, Valerie
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Publisher
Australasian Medical Association
Abstract
Objective: To determine if the recent rapid fall in use of hormone replacement therapy (HRT) in Australia has been followed by a reduction in breast cancer incidence among women aged 50 years or older, but not among younger women. Design and setting: Analysis of trends in annual prescribing of HRT, using Pharmaceutical Benefits Scheme data, and in annual age-standardised breast cancer incidence rates in Australian women for the period 1996-2003. Results: In Australia, prescribing of HRT increased from 1996 to 2001, but dropped by 40% from 2001 to 2003. Age-standardised breast cancer incidence rates in women aged ≥ 50 years also increased to 2001 but declined thereafter. The incidence rates in this age group were lower by 6.7% (95% CI, 3.9%-9.3%; P < 0.001) in 2003 compared with 2001, equivalent to 600 (95% CI, 350-830) fewer breast cancers (out of about 9000 incident breast cancers annually for women this age). There was no significant change in breast cancer incidence for women aged < 50 years. Conclusions: While other factors may have contributed to a recent reduction in breast cancer incidence among Australian women aged ≥ 50 years, the available evidence suggests that much of the decrease is due to the recent fall in use of HRT. This is consistent with other evidence that the HRT-associated increase in risk of breast cancer is reversible after ceasing use of HRT.
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Keywords
Keywords: adult; age distribution; article; Australia; breast cancer; cancer incidence; cancer risk; cancer susceptibility; female; hormone substitution; human; major clinical study; prescription; risk reduction; trend study
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Source
Medical Journal of Australia
Type
Journal article
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2037-12-31
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