United States researchers have recently brought forth new evidence linking hormone replacement therapy (HRT) to high risk of developing breast cancer.

The study conducted by the New England Journal of Medicine revealed that the risk of breast cancer significantly decreased when women stopped undergoing HRT.

Moreover, a United Kingdom expert stated that a 50 percent drop in the use of HRT had probably prevented the development of breast cancer in approximately 1,000 women annually.

Nevertheless, other experts have voiced their belief that the decrease registered in the number of breast cancer cases was prompted by other factors.

The California researchers said that after the year 2002, when combined oestrogen and progestin HRT was dropped from use, breast cancer rates fell considerably, which proved that a connection between the therapy and the disease existed.

Still, some have claimed that the drop in breast cancer rates had been the result of, among others, women having reduced the frequency of mammograms after they had stopped undergoing HRT.

The new study continued to monitor 15,000 women that participated in the original 2002 "Women's Health Initiative" study that linked HRT with breast cancer risk, while it also looked at women who had not been involved in the 2002 research and who unlike the ones in that study, had not received any advice concerning dropping HRT.

In the first group, breast cancer rates were much higher within the five-year time-frame before the 2002 study was initiated, while after the women were told to stop HRT, the rates decreased by 28% in 12 months.

In the second group, many participants decided to drop HRT, as well, which coincided with a 43% fall in breast cancer rates between 2002 and 2003.