Hormone Replacement Therapy May Increase Risk of Ovarian Cancer

The dangers that lurk in the use of hormone replacement therapy (HRT) have once again been pushed to the forefront of conscious awareness. Women currently taking HRT, as well as those who have taken it in the recent past, are at an increased risk of developing ovarian cancer. Scientists have known for some time that the use of HRT by women increases the odds of developing breast cancer.  In addition, studies have shown that HRT more than doubles the risk of lung cancer death in women who develop lung cancer. A Danish study recently published in the Journal of the American Medical Association found that women who had undergone HRT for menopausal symptoms has an increased likelihood of developing ovarian cancer, regardless of the length, formulation or type of treatment they received.

HRT is a treatment used for women who experience severe hormone withdrawal symptoms during the post-menopausal phase. The therapy helps to alleviate or prevent symptoms such as mood swings, hot flashes, and the emotional repercussions of the loss of fertility when the ovaries stop producing. HRT administers an artificial boost of the diminished hormones such as estrogen, progesterone, and in some cases, even testosterone.

The results of a study of more than 900,000 Danish women aged 50 to 79 showed that about one additional ovarian cancer annually occurred for approximately every 8,300 women taking HRT. Current HRT users were found to have a 38 percent increased risk of ovarian cancer as well as a 44 percent increased risk of a type of cancer that begins in the outer lining of the ovary, known as epithelial ovarian cancer, when compared to women who had never taken HRT.

Over the eight-year analysis performed by study lead Lina Steinrud Morch and colleagues at Copenhagen University, 9 percent of the women who developed cancer were taking HRT, while 22 percent were previous HRT users, and 63 percent had never taken the therapy.

According to Morch, “Our study underlines previous evidence that postmenopausal hormones increase the risk of ovarian cancer.” Regarding the low incidence of addition cancers that occurred she noted, “Even though this share seems low, ovarian cancer remains highly fatal, so accordingly this risk warrants consideration when deciding whether to use (hormone therapy).” She then added, “Ovarian cancer is the most lethal of gynecologic cancers. The five-year survival rates are 40 percent. Only a few risk factors for ovarian cancer are modifiable.”

During the eight years of follow-up, the researcher team found 3,068 cases of ovarian cancer, with 2,681 being epithelial ovarian cancers. A decrease in the risk of ovarian cancer was noted immediately after women stopped taking hormones. However, those women who had just halted HRT still had a 22 percent increased risk of ovarian cancer compared to those who were off for less than two years. The cancer risked diminished to normal with two to four years after stopping HRT.

The study findings coincide with those in the 2002 Women's Health Initiative study that was halted early due to the discovery of an increased risk of ovarian cancer, breast cancer and stroke, as well as other health problems stemming from HRT use.

Morch acknowledged that the research team was unable to adjust the data to account for family history or for prior use of birth control, and noted that this could result in an underestimation of the ovarian cancer risk. However, Morch also pointed out, that ovarian cancer is still a rare disease. She emphasized, “Despite a 40 percent increased risk of ovarian cancer among current users of hormones, each woman will still have a very low absolute risk of developing cancer due to her hormone use. We think that hormones may still have a therapeutic place in women with severe perimenopausal symptoms and among women going into premature menopause.”

Wyeth, maker of Premarin and Prempro, two conjugated estrogens, argued that the study did not include a sufficient number of women on conjugated estrogens to determine the actual risk for this particular type of hormone therapy. In a prepared statement, the company held, “The findings in this study do not change what we already know about the benefits and risks of hormone therapy, which is based on data from multiple studies. Hormone therapy remains a good health-care choice for the appropriate woman seeking relief from moderate to severe menopausal symptoms.”

Although the cause of ovarian cancer remains unknown, estrogen is highly suspect of triggering tumor growth. Ovarian cancer is very difficult to detect prior to its spread, often making it a fatal disease. About 18 out of each 100,000 women in the United States are diagnosed with ovarian cancer annually. In 2007 alone, the disease claimed the lives of 15,000 Americans, according to government statistics.