Influence of the dramatic fall of HRT prescription on postmenopausal breast cancer incidence: The Austrian Data

Background: The Women's Health Initiative trial showed a significant increase in breast cancer risk among women using HRT. This publication led to a dramatic fall in HRT prescription worldwide. Several studies argued that the ensuing decline in breast cancer incidence among postmenopausal women was due to the reduced HRT prescriptions. We have investigated whether the strong decline in HRT prescription in Austria from 2002 onwards was associated with a decrease in postmenopausal breast cancer incidence.

Methods: Breast cancer incidence data were obtained from the National Austrian cancer registry. HRT prescription data were calculated using Pharmaceutical Benefits Scheme data. Hormone receptor expression data were taken from the pathology report of all breast cancer patients operated at the Medical University of Vienna, during 1998–2000, and 2005–2007, respectively. Chi Square test was used to identify significant differences.

Results: HRT prescription slightly increased from 1998 to 2000, but dramatically decreased by 70% after 2003, reaching a significantly lower level. When comparing breast cancer incidence data from 1999 and 2004, a non significant trend towards a decreased incidence in 50–54 years old women could be observed. Comparing predicted breast cancer incidence of 2004 with the actual incidence of 2004 in this group, a significant decrease could be demonstrated. Regarding histo-pathologic breast cancer parameters a non significant decline of hormone receptor positive tumors in 50–54 years old breast cancer patients could be observed.

Conclusion: The decline of HRT use in Austria is associated with a reduction in breast cancer incidence in postmenopausal women. Our data underline the association between HRT and breast cancer.