Consumer Drug Report
Possible breast cancer risk for menopausal women on estrogen

Women combatting menopause with estrogen alone face increased breast cancer risk, according to a study presented at this week’s American Association for Cancer Research conference in Chicago. This information contradicts what was said at the AACR conference held in San Antonio, Texas, in December 2010. It also contradicts a 12-year study published online last month by Lancet Oncology.

In 2010, lead researcher, medical oncologist and clinical professor Joseph Ragaz, M.D., of The University of British Columbia, Vancouver, said that taking estrogen alone was not only safe but potentially beneficial.

“These findings should intensify new research into its role as a protective agent against breast cancer,” Ragaz said.

Lancet Oncology’s research seemed to support that.

“Estrogen on its own appears to be safe,” said University of Manchester professor of medical oncology Anthony Howell, who co-wrote commentary on the study. Though uncertain why estrogen appeared to lower the risk of breast cancer, he said that fluctuating estrogen levels may interfere with tumor development.

Out of 7,600 women aged 50 to 79 who had a hysterectomy, fewer women taking estrogen developed breast cancer during the study than those taking placebo pills (151 to 199, respectively). Six taking estrogen died, opposed to 16 taking the placebo.

This weekend, however, the AACR stated that 60,000 nurses taking any kind of hormone for 10 years or longer increased their chances of developing breast cancer, even once they’d stopped taking it.  Worse, said Dr. Wendy Chen, assistant professor in medicine at Dana-Farber Cancer Institute in Boston, Mass., the risk did not appear to plateau.

"It's hard to be surprised that if you keep taking it, sooner or later it's going to raise risk," said Dr. Robert Clarke of Georgetown University's Lombardi Comprehensive Cancer Center.

U.S. -funded Women's Health Initiative began studying estrogen therapy’s link to breast cancer risk in the 1990s.The group ended a 2002 trial of 16,000 women aged 50 to 79 when a combination of hormones estrogen and progestin were found to increase the risk of strokes, heart, disease, and breast cancer.

The combination correlated to 385 invasive breast cancer cases compared to 293 in the placebo group.  However, the estrogen-plus-progestin group was more likely to be node-positive (81 cases to 43, respectively), making participants nearly twice as likely to die of breast cancer than the placebo group.

The Canadian Medical Association Journal states that the presence of cancer cells in the lymph nodes means that there is a higher chance of the cancer returning and spreading.

Tens of millions of prescriptions are written each year for postmenopausal symptoms like hot flashes, insomnia, night sweats, and mood swings.

Chen said women should discuss symptoms with their doctor, who may be able to prescribe something other than hormone replacement therapy.

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