All women who take hormone replacement therapy (HRT) increase their chances of developing breast cancer. It had been believed that only those with a family history of cancer were at risk.
Researchers overturned the long-held belief after they tracked the health of 16,608 post-menopausal women aged from 50 to 79, who had taken either an HRT drug or a placebo pill between 1993 and 2002. In that time 349 women developed breast cancer, but researchers couldn't find any link with family history.
The research team, from the University of Rochester Medical Center, say it is yet another factor for women to weigh up when thinking about starting HRT.
(Source: Epidemiology, 2009: doi: 10.1097/EDE.0b013e3181a71279).