Last Updated:  07/19/2009

The information in this column is intended for informational purposes only, and does not constitute medical advice or recommendations by the author.  Please consult with your physician before making any lifestyle or medication changes, or if you have any other concerns regarding your health.

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HORMONE REPLACEMENT THERAPY (HRT) & OVARIAN CANCER

By now, regular readers of this column already know that combination hormone replacement therapy (HRT) drugs, which have been taken by millions of postmenopausal women since World War II, have been unequivocally linked to a significant increase in the risk of breast cancer and heart disease (see my other columns on this topic, if you are not yet aware of these findings from the seminal Women’s Health Initiative Study).   Now, a new prospective public health study from Denmark, which has just been published in the Journal of the American Medical Association, strongly suggests that the risk of ovarian cancer may also be significantly increased by chronic HRT use.

 

In this newly published study, all Danish women between the ages of 50 and 79 years were followed between 1995 and 2005, using prospective public health databases.  Altogether, a whopping 909,946 women were included in this study’s analysis.

 

After an average follow-up duration of 8 years, 3,068 new cases of ovarian cancer were diagnosed.  Using a national pharmacy registry, the researchers conducting this study were able to review all of the medications previously and currently taken by the nearly 1 million women who were included in this public health study.

 

When compared to women who had never used HRT, current users of HRT experienced a 38 percent increase in the incidence of ovarian cancer.  Among women who had previously used HRT, the risk of developing ovarian cancer decreased with each passing year after discontinuing HRT.  Within two years of discontinuing HRT, the risk of developing ovarian cancer had returned to the same level that was observed among women in the general population who had never used HRT.  Interestingly, unlike the current data linking combination HRT with breast cancer, the increased risk of developing ovarian cancer with HRT use was associated with both combination HRT and with estrogen-only HRT.

 

Ovarian cancer is a relatively rare form of cancer, with approximately 22,000 cases diagnosed each year in the United States.  Therefore, ovarian cancer accounts for fewer that 1.5 percent of all diagnosed cancers, overall, and approximately 3 percent of all cancers occurring in women.  However, ovarian cancer is a fairly lethal disease, with a nearly 70 percent mortality rate based upon 2009 statistics from the American Cancer Society.  Thus, even a relatively modest increase in the risk of developing ovarian cancer translates into a potentially significant number of deaths from this disease.   (The authors of this study calculated that one woman would go on to develop a preventable case of ovarian cancer for every year of HRT taken within a group of 8,330 women.)  When the researchers applied these findings to the incidence of ovarian cancer in Denmark, they concluded that approximately 5 percent of the total number of cases of ovarian cancer in Denmark could be linked to the use of HRT.

 

Another finding of particular interest in this study was that the use of estrogen skin patches (transdermal HRT) and vaginal estrogen creams were also associated with a mild increase in the risk of developing ovarian cancer.  I point this finding out, as there are advocates of these alternative forms of HRT who claim that they are not associated with any known cancer risk, unlike the more common oral forms of HRT. 

 

Thus, this enormous prospective public health study strongly suggests that HRT use, of any type, is associated with a small but potentially significant increase in the risk of developing ovarian cancer (unlike, I might add, low-dose oral contraceptive medications, which have been linked to a lower risk of developing ovarian cancer).  On the other hand, the increased risk of ovarian cancer associated with HRT appears to essentially disappear approximately two years after discontinuation of HRT.

 

This is not the first clinical research study linking HRT to an increased risk of ovarian cancer, and the findings of this huge study further underscore the potentially adverse effects of HRT on a woman’s health.  (Although this was not a randomized placebo-controlled clinical trial, the huge number of patients included in this study adds considerable statistical power to its findings.)  Indeed, since the ominous findings of the prematurely terminated Women’s Health Initiative Study were first revealed in 2002, I have counseled my own patients to avoid HRT if at all possible.

 

(Note:  The post-World War II marketing history for HRT is a fascinating but disturbing story of drug company hubris and the collective complicity of much of the mainstream medical profession, and it is a cautionary tale that I will be telling in a new book, due to be published at the end of 2010.)

 

Disclaimer:  As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity

 

Dr. Wascher is an oncologic surgeon, a professor of surgery, a widely published author, and the Physician-in-Chief for Surgical Oncology at the Kaiser Permanente healthcare system in Orange County, California

  

 

(Anticipated Publication Date:  March 2010)

(Click above image for TV36 interview of Dr. Wascher)