HRT Linked to Breast Cancer


H.R.T. Three letters every menopausal woman comes to know intimately. HRT, or Hormone Replacement Therapy, has long been given to menopausal and post-menopausal women in as a substitute for the hormones they no longer produce, estrogen and progesterone, after menopause. It was thought to have multiple health benefits such as reduced risk of heart disease and dementia.

It was even thought that HRT might reduce the risk of breast cancer, however when clinical trails were performed, the opposite was found.

Since 1999 there have been multiple studies done both in the U.S. and the U.K. in an attempt to discern the link, if any, between HRT and breast cancer. The correlation has been all over the proverbial map with one study in the U.K. — under the moniker "the Million Women Study" — was thought to have discovered a 50% greater chance of breast cancer in women who had used HRT. This study was found to have shoddy results, and usually the study most referenced is a 2002 study performed by the Women’s Health initiative (WHI). The study was supposed to continue for five years but was halted early due to the increased risk of stroke. 

There was a follow up to this study over approximately 11 years, which concluded that there is in fact a link between breast cancer and combined (estrogen and progesterone) HRT. The results recently published indicate that there is an annualized breast cancer rate of 0.60% for women taking HRT as opposed to a 0.42% risk for women who are not on HRT.

Out of 41,449 women (who had all received a negative mammogram within two years of beginning the study), 16,121 were on HRT. Out of all participants, during follow up, there were 2236 invasive breast cancers. The survival rate after diagnosis was similar for users and non-users; the users had a slightly higher mortality risk than non-users though the difference was not deemed statistically relevant.

So now the question is, does this mean the end for HRT?

The answer: likely not.

Even after the initial results of the Million Women Study indicated a high correlation between breast cancer and HRT, the news only briefly reduced the number of women using HRT to treat the symptoms of menopause. Though it now seems wise to use the drug for the shortest term possible to reduce potential risk of breast cancer, the drugs are still widely prescribed to treat the often intense symptoms of early menopause, as they are the only drugs that provide relief. Additionally, there seems to be greater health risks when HRT users are older — 63+ — and for users who take estrogen alone without progesterone. This suggests perhaps there will be an increase in combined HRT as opposed to what’s referred to as ET, an HRT that only contains estrogen.