Estrogen and progestin: Hormone therapy to die for?

April 1, 2013 | by Roberta Nichols

For more than a decade, hormone therapy – once believed to improve cardiovascular, bone and cognitive health and control extreme menopausal symptoms such as hot flashes and night sweats – has been linked to a higher incidence of breast cancer.

Taking hormone therapy for menopausal symtpoms is increasingly seen as a roll of the dice. Taking hormone therapy for menopausal symptoms is increasingly seen as a roll of the dice.

Yet, previous studies suggested that such breast cancers were not likely to be lethal, so some women have continued to roll the dice and take the estrogen and progestin combination, a synthetic version of the natural hormone progesterone.

A new study, however, suggests that women should reconsider whether they can live with these symptoms – or boost their chance of dying from this therapy that relieves them.

The findings were published in the March 29 edition of the Journal of the National Cancer Institute.

Researchers led by Rowan T. Chlebowski, M.D., Ph.D., a medical oncologist at the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, analyzed results from the Women’s Health Initiative Observational Study. They compared the findings with those from the Women’s Health Initiative randomized clinical trial, in which women were assigned to different treatments.

“In the Women’s Health Initiative (WHI) randomized trial, estrogen plus progestin increased both breast cancer incidence and mortality,” wrote Chlebowski in the study. “In contrast, most observational studies associate estrogen plus progestin with favorable prognosis breast cancer. To address differences,” he added, “a cohort of WHI observational study participants with characteristics similar to the WHI clinical trial was studied.”

Researchers analyzed the cases of women over an average of 11 years. Of the 41,449 women whose cases they reviewed, 25,328 did not use hormone therapy, and 16,121 used the estrogen/progestin combination. More than 2,236 women developed breast cancer. This analysis excluded estrogen-only therapy, used by women who underwent hysterectomies.

One of the issues Chlebowski sought to explore was whether the link between breast cancer risk and combined hormone therapy had been influenced by earlier use of hormones. The results were surprising.

The new findings suggest that “the time of starting hormone therapy really matters,” Joanne Mortimer, M.D., director of City of Hope’s Women’s Cancers Program, told Healthday. She was not involved in the study.

“Women starting (hormones) within months of menopause had about a threefold greater risk than women starting 10 years after menopause,” Chlebowski told Healthday.

He theorized that women beginning hormone therapy close to menopause “still have circulating levels of estrogen high enough to make them exceed some threshold, beyond which it may become hazardous.”

Mortimer and Chlebowski agreed that though previous studies demonstrated positive effects of hormone therapy for the heart, this must be weighed against the mounting evidence that combined hormone therapy increases the odds of getting breast cancer risk – and dying from it.

In a Los Angeles Times interview, Mortimer said she normally does not  recommend hormone therapy for patients with menopause symptoms, but for “the ones who are up all night with hot flashes and want to kill people,” hormones seem to provide the only relief.

She continues to discuss the pros and cons with her patients and urges that women have this conversation with their own physicians.

With this new study, the “cons” list has just gotten longer.

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