Top U.S. & British medical journals report–Hormone drugs from pregnant mare’s urine can cost lives & minds
From ANIMAL PEOPLE, September 2003:
LONDON–Sales of hormone supplements made from pregnant
mare’s urine, already down 65% in less than a year, may fall even
faster after the August 9 publication by the British Medical
Association journal The Lancet of new evidence that taking popular
combinations of estrogen and progestin appears to produce a 66%
greater risk of developing breast cancer within five years, and a
22% greater risk of dying from it.
Taking estrogen alone increased the risk of developing breast
cancer by 30%.
The data came from clinical observation of nearly one million
British women between the ages of 50 and 64, who were surveyed at
annual mammogram appointments beginning in 1996.
The $10 million study was directed by Valerie Beral, M.D.,
of Oxford University, with funding from the British government and
Cancer Research U.K., a private charity.
Beral and team estimated that taking estrogen/progestin
combination drugs could be linked to 15,000 more cases of breast
cancer during the past 10 years than would otherwise have occurred.
Taking estrogen alone could be associated with 5,000 additional cases.
Together with new findings published in recent editions of
the Journal of the American Medical Association and New England
Journal of Medicine, the British data may virtually halt consumer
demand for drugs derived from pregnant mare’s urine, called PMU for
JAMA on May 28 reported that women taking hormone
supplements have a doubled risk of developing Alzheimer’s disease and
other forms of senile dementia.
The New England Journal of Medicine on August 7 reported that
a woman’s risk of a heart attack is 81% higher than the norm for her
age in her first year of hormone therapy, and 24% higher over five
The PMU production process, which treats horses much like
factory-farmed dairy cattle, became subject of a gobal boycott by
more than 50 leading animal advocacy groups after it was exposed on
page one of the April 1993 edition of ANIMAL PEOPLE.
Based on investigative findings by Canadian Farm Animal Care
Trust founder Tom Hughes, the ANIMAL PEOPLE report was amplified by
three of the five leading New York City newspapers, and won the
International Generic Horse Association/HorseAid “Equine Awareness in
Media” award. The boycott was declared later in 1993 by PETA,
Friends of Animals, the Animal Protection Institute, and the World
Society for the Protection of Animals.
At the time, PMU producers in the prairie provinces of
Canada and the Dakotas were sending an estimated 70,000 foals and
“retired” mares to slaughter each year, and the industry was
expanding production facilities, anticipating a surge of demand as
the Baby Boom generation hit menopause.
The boycott by 2000 appeared to have cut the number of
operating PMU farms by 15% and to have halved the number of horses
involved in PMU production.
But that was slight compared to the crash after the Women’s
Health Initiative on July 9, 2002 warned participants in a nine-year
federally funded study involving 16,000 women that for each 10,000
women who take the Wyeth Pharmaceuticals estrogen/progestin drug
Prempro for one year, there are eight more cases of invasive breast
cancer than among women of the same age range and state of health who
do not take the drug, plus seven more heart attacks, eight more
strokes, and eight more cases of blood clots in the lungs.
As many as six million women were reportedly taking hormone
supplements as of July 2002, including 3.4 million users of Prempro.
By July 2003, Wyeth acknowleged, only 2.7 million women were still
using hormone supplements, and only 1.2 million continued to use
Prempro. Wyeth stock fell in value by 52% between May and mid-July
2002, but total Wyeth sales of hormone supplements dipped just 25%
because Wyeth also manufactures the most popular alternatives to
Prempro for women who choose to continue taking supplemental estrogen.
The July 2002 Women’s Health Initiative warning addressed
only estrogen/ progestin combination drugs.
More about the WHI findings appeared in the June 25, 2003 edition of
the Journal of the American Medical Association.
U.S. women who take estrogen/ progestin combination supplements are
more likely to develop breast cancer, WHI reaffirmed after further
refinement of the data.
Worse, women taking the estrogen/progestin combination drugs are
more likely to develop particular types of tumor that tend to be
discovered at a later stage of development, with less chance of
Summarized New York Times medical writer Denise Grady, “Of
the 8,506 women on hormones in the study, 199 developed invasive
breast cancers, compared with 150 cases in the 8,102 women taking
placebos. In the women using hormones, 25.4% had cancers that
spread either to nearby tissue or distant parts of the body,
compared with only 16% in the placebo group.
“In addition,” Grady wrote, “after one year of treatment,
9.4% of women in the hormone group had abnormal mammograms, as
opposed to only 5.4% in the placebo group. The risk of an abnormal
mammogram translates into 1 in 25 treated women per year.”
The Women’s Health Initiative also furnished the data behind
the New England Journal of Medicine report linking hormone
supplements with higher risk of heart attacks.
The association of hormone therapy with Alzheimer’s disease
and senile dementia emerged from a separate four-year study of 4,532
women at 39 U.S. medical centers, funded by the Alzheimer’s
Association. The investigators hoped to find that hormone therapy
might prevent Alzheimer’s.
Instead, explained Grady, “There were 40 cases of dementia
in the hormone group and 21 in the placebo group. Translated to an
annual rate for a larger population, the results mean that for every
10,000 women age 65 and older who take hormones, there will be 45
cases of dementia per year, with 23 of them attributable to the
Commented Clifford Hudis, M.D., chief of breast cancer
medicine at the Memorial Sloan-Kettering Cancer Center in New York
City, “The whole health benefit story for hormones has really
In December 2002 the U.S. National Institute of Environmental
Health Sciences listed all estrogens used for hormone replacement and
contraceptive purposes as known human carcinogens.
This includes all estrogens made from pregnant mare’s urine.
Developed initially by Ayerst Pharmaceuticals of Montreal, later
purchased by Wyeth, PMU-based estrogen supplements and birth control
pills had been marketed in the U.S. since 1942.
Wyeth added a warning of the suspected health risks to the Prempro
label in August 2002. In January 2003 the U.S. Food and Drug
Administration ordered that a warning be added to all labels for
hormonal products for menopausal women that the drugs may slightly
increase their risk of heart attack, stroke, blood clots, and