Two new studies further reinforce the belief HRT is indeed a high risk factor for developing breast cancer and ovarian cancer. The first study by US researchers found breast cancer rates declined significantly following heart, stroke and breast cancer fears. The second study in Britain said HRT after menopause was responsible for a 20 percent increased risk of ovarian cancer.

Hormone therapy involves the intake of synthetic analogues of the hormones estrogen and progestin. Following menopause the level of these hormones in a woman's body falls drastically, leading to typical menopausal symptoms like hot flashes and night sweats.

HRT is most often used to treat symptoms of menopause such as vaginal dryness, mood swings, sleep disorders, and decreased sexual desire. Some women taking HRT may experience water retention, bloating, nausea, breast soreness, mood swings, and headaches.

In 1993 a large study was launched by the Women's Health Initiative in order to explore links between HRT use and breast cancer risk. The findings of the study led millions of women to discard the option of HRT altogether.

Researchers at the University of Texas M. D. Anderson Cancer Center analyzed cancer rates following a drop in the use of HRT. There was a steep dip in new diagnoses of breast cancer in mid-2002 and continued into 2003 as well, researchers report in the New England Journal of Medicine.

Estrogen-receptor(ER)-positive cancers declined 14.7 percent in the three years from 2002-2004. This was true in the age group of 50 to 69 years. Hormone positive breast cancer is thought to be fuelled by the excess estrogen from HRT.

Researchers theorize a fall in HRT may have contributed to the less number of new hormone positive breast cancers during the study period. "For our new data set, 2004, the drop in breast cancer incidence leveled off and remained low in that year,” said Peter Ravdin is a cancer specialist at the M.D. Anderson Cancer Center.

Researchers admit other factors like environment and diet may have played a role in the decline of breast cancer rates, but lead researcher Dr Donald Berry called the findings a smoking gun. He added they could never be sure of the HRT and breast cancer link, but the findings do provide a strong association.

Following the revelations of the WHI study launched in 1993, doctors have hesitated to prescribe hormones to reduce menopausal symptoms. The National Institutes of Health cites several risks including breast cancer, stroke, blood clots and ovarian cancer.
The link of HRT to ovarian cancer was the subject of the second study called the Million Women Study in Britain. Reporting in the Lancet medical journal, researchers said HRT increases the risk of women developing ovarian cancer.

Researchers at the Cancer Research UK Epidemiology Unit in Oxford said at least 1,000 extra women had succumbed to ovarian cancer in Britain between 1991 and 2005 because they used hormone replacement therapy.

In the study over 50 percent of the million women participating were either current or former HRT users. Around 2.6 women of every 1,000 that used HRT after menopause developed ovarian cancer as compared to 2.2 cases of ovarian cancer for every 1,000 non-HRT women.

"The effect of HRT on ovarian cancer should not be viewed in isolation, especially since use of HRT also affects the risk of breast and endometrial cancer," the researchers, led by Dr. Valerie Beral wrote. "The total incidence of these three cancers in the study population is 63 percent higher in current users of HRT than never users."

Doctors always recommend the lowest possible dose for HRT. However the National Cancer Institute in the US suggests that HRT must be used with caution, "Breast cancer is the most frequently diagnosed cancer among women in the United States, and we have made great strides in its treatment," said NCI Director, Dr John E. Niederhuber. "Finding the simple ways, such as limiting HRT use to decrease breast cancer risk, is a step forward."

Meanwhile Wyeth Pharmaceuticals said the US study was misleading, "Hormone therapy remains a good health care choice for the appropriate woman seeking the relief of moderate to severe menopausal symptoms," Dr Joseph Camardo, Senior Vice President of Global Medical Affairs for Wyeth Pharmaceuticals said.

One thing is certain. HRT does increase cancer risk either directly or indirectly. That is why it is important consumers always consult their doctors before starting off on any hormones to relieve menopausal symptoms.