Breast Cancer: HRT may be a bigger cause than everyone thought

Hormone replacement therapy (HRT) may have been a bigger cause of breast cancer than anyone suspected.  Since sales started tailing off in 2002 with the news of its carcinogenic effects, rates of breast cancer around the world also began to fall.

Although breast cancer is still the most common cancer in women, rates of new cases are at an all-time low in Australia, the USA, New Zealand, Canada, Germany and France.

Australian researchers discovered the downward trend there was among women aged 50 and older when they were more likely to start taking HRT.  This pattern has been repeated in other countries and, while some argue the reduction is due to improved screening, researchers in 2007 established a direct link between the cancer and HRT use in the USA.
Norwegian researchers have noticed a similar decline, and one that is in line with the fall in HRT use.

(Source: The Lancet, 2008; 372: 608-10).