The risk of more deadly forms of breast cancer has been shown to increase through the use of hormone replacement therapy, according to a study.
Death rates among women with the cancer doubled in those who had HRT for an average 5.6 years.
The link between breast cancer and HRT among post-menopausal women has already been established thanks to the large-scale Women’s Health Initiative (WHI) study in the US.
Now new findings from the WHI show that use of oestrogen plus progestin hormone therapy increases the incidence of more advanced forms of breast cancer. It is also associated with a higher risk of deaths attributed to the disease.
Women taking part in the study were either given combination HRT or a dummy “placebo” pill. Almost 13,000 women consented to having their condition monitored for an extended 11-year period after treatment.
Invasive breast cancer occurred in 385 women who received hormone treatment, compared with 293 who did not. A significantly larger percentage of women in the HRT group had breast cancers that had spread to the lymph glands.
A total of 25 women among the HRT group and 12 among the placebo group died from breast cancer. At a population level, this is the equivalent of 2.6 against 1.3 deaths per 10,000 women per year.
The findings appeared in the Journal of the American Medical Association.
Copyright Press Association 2010