March 15, 2013

expert reaction to HRT and breast cancer

A study in the Journal of Family Planning and Reproductive Health Care found there was no clear evidence in the data it examined of a causal link between the decline in the use of hormone replacement therapy (HRT) and a reported fall in the numbers of new cases of breast cancer. A before the headlines analysis accompanied this roundup.

Prof Valerie Beral, Professor of Epidemiology at the University Of Oxford, said:

“I don’t think this paper really tells us anything about HRT as a cause of breast cancer.  Scientists would rarely – if ever – infer cause and effect from cancer trends.  Breast cancer trends can be influenced by many factors including childbearing patters, changes in obesity, alcohol consumption, and screening practices; so the effect of HRT simply can’t be teased out by looking at trends alone.

“What we do know from several dozen studies is that, almost without exception, use of HRT increases the risk of breast cancer; and when use is stopped the risk goes away within about 5 years.”

‘Does hormone replacement therapy (HRT) cause breast cancer?  An application of causal principles to three studies’ by Samuel Shapiro et al published in the Journal of Family Planning and Reproductive Health Care on Thursday 14th March.