Hormone Replacement Therapy Increases Ovarian Cancer Risk

What You Need to Know: Taking hormone replacement therapy (HRT) for menopause, even for just a few years, is associated with a small increased risk of developing the two most common types of ovarian cancer, according to a detailed re-analysis of all the available evidence.

The Evidence: The findings from a meta-analysis (a study of a collection of studies) of 52 epidemiological studies, involving a total of 21488 women with ovarian cancer, almost all from North America, Europe and Australia, indicate that women who use HRT for just a few years are about 40% more likely to develop ovarian cancer than women who have never taken HRT.

“For women who take HRT for 5 years from around age 50, there will be about one extra ovarian cancer for every 1000 users and one extra ovarian cancer death for every 1700 users”, explains study co-author Professor Sir Richard Peto from the University of Oxford in the UK.

The effect of HRT on the risk of developing ovarian cancer was the same for the two main types of HRT (preparations containing oestrogen only, or oestrogen together with a progestagen). Likewise, the proportional increase in risk was not materially affected by the age at which HRT began, body size, past use of oral contraceptives, hysterectomy, alcohol use, tobacco use, or family history of breast or ovarian cancer.

There are, however, four main types of ovarian cancer, and an increase in risk was seen only for the two most common types (serous and endometrioid ovarian cancers), and not for the two less common types (mucinous and clear cell ovarian cancers).

My Take: While hormone replacement therapy can provide benefits for selected individuals, this study reminds us to be prudent: If you must use HRT (for example, for hot flashes not controlled by acupuncture, exercise, and attention to triggers such as heat, caffeine, alcohol, stress, and spicy foods), use the lowest dose of HRT that you can, for as short a duration as possible. HRT can also increase the risks of breast cancer and cardiovascular events (but may lower your risk of colon cancer, and help with hot flashes (among other symptoms of menopause). I’m Dr. Michael Hunter.

References: 

  1. Collaborative Group on Epidemiological Studies of Ovarian Cancer. Menopausal hormone use and ovarian cancer risk: individual participant meta-analysis of 52 epidemiological studies. The Lancet, 2015 DOI: 10.1016/S0140-6736(14)61687-1
  2. The Lancet. “Short-term use of hormone replacement therapy associated with increased ovarian cancer risk.” ScienceDaily. ScienceDaily, 12 February 2015. <www.sciencedaily.com/releases/2015/02/150212211945.htm>.

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understandcancerin60minutes

Harvard AB Yale MD UPenn Radiation Oncology Radiation Oncologist, Seattle area

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