Withdrawing hormone replacement therapy (HRT) from women reduces the risk of breast cancer, Canadian researchers have shown.
The new study has thrown the safety of hormone replacement into further doubt.
The researchers found that a decrease in the number of menopausal women taking HRT has coincided with a 10 per cent decrease in cancer rates.
Fears over the treatment's safety were first raised in 2002 when a major U.S. study linked it to breast cancer, heart disease and strokes.
It led to thousands of British women abandoning the pills, and within three years the numbers using it had halved to one million.
But its link to breast cancer has since been disputed and in 2007 another study found that the risks applied only to those in their 70s and 80s - much older than women who usually take HRT.
Now Canadian researchers have found that the decline in use of HRT prompted by the health scares coincided with a 10 per cent fall in breast cancer rates in their country, reports the Daily Mail.
They found the biggest decline in use of HRT was between 2002 and 2004, when the proportion of women taking it fell from 12.7 per cent to just 4.9 per cent.
Over the same period, the number of breast cancer diagnoses fell by 9.6 per cent.