| NICHD Study Shows Fibroid Tumors Unlikely To Respond To Conventional Hormone Treatments
Finding Suggests Strategies for New Treatments
A new study suggests that the conventional hormone therapies used
to treat fibroid tumors are unlikely to produce much improvement
and at best will only temporarily relieve symptoms. However, the
study findings also suggest a strategy for developing a new, non-surgical
Fibroid tumors — the sometimes painful uterine growths affecting
many American women — are made up largely of abnormal collagen,
a protein that doesn’t respond to reproductive hormones, according
to the study, which was conducted by researchers at the National
Institute of Child Health and Human Development of the National
Institutes of Health.
"This finding is an important step in understanding the nature
of fibroids and offers a potential strategy for treating them without
surgery," said Duane Alexander, M.D., Director of the NICHD.
"NICHD researchers are preparing a study of drug treatments
that may prevent fibroids from forming or dissolve them after they
The study appears in the October 2004 issue of Fertility and Sterility
and was supported by NICHD and the National Naval Medical Center
in Bethesda, MD.
Fibroids, or leiomyomas, are noncancerous growths that develop
in the myoemetrium, the smooth muscle tissue of the uterus, explained
the study’s first author, Phyllis Leppert, M.D., Ph.D., Chief
of NICHD’s Reproductive Science Branch.
Women with fibroids may have painful menstrual periods, pain during
sexual intercourse, infertility, urinary and fecal incontinence,
and bowel obstruction, Dr. Leppert said. They are also more likely
to go into labor prematurely and to experience a miscarriage.
It is not known how many U.S. women have fibroids. In many cases,
fibroids do not cause symptoms, making it difficult to detect them.
However, some studies indicate that, in the United States, from
25 to 40 percent of all U.S. women experience symptoms from fibroids.
Fibroids disproportionately affect African Americans, with one study
estimating that 80 percent of African American women are affected
by the growths by age 60.
For women who experience severe symptoms, treatment often involves
surgery. In one form of surgery, myomectomy, the fibroids are removed
from the wall of the uterus. In many cases, the fibroids return
after surgery or their removal results in the formation of painful
scar tissue. In other cases, the number of fibroids is so great
that hysterectomy (removal of the uterus) must be performed. Uterine
fibroid embolization, an experimental treatment, involves using
a catheter threaded through an artery to shut off the flow of blood
supplying the fibroid. The experimental therapy carries the risk
of damaging surrounding areas of the uterus.
According to the Centers for Disease Control and Prevention, fibroids
account for 68 percent of hysterectomies among black women, 33 percent
in white women, and 45 percent of women of other races.
In some cases, fibroids are treated with a leuprolide, a drug that
halts production of reproductive hormones and brings on a temporary
menopause. In other instances, physicians have attempted to treat
fibroids with a combination of estrogen and progestin, the principal
ingredients in oral contraceptives and menopausal hormone therapy.
In the current study, Dr. Leppert and her colleagues performed
a microscopic analysis of fibroid tumors and normal uterine tissue
collected from 5 women who had undergone hysterectomy for fibroids.
Dr. Leppert explained that collagen fibrils — the miniscule
"threads" of collagen visible under an electron microscope
— are normally arrange in a neat, orderly pattern, parallel
to each other. In the fibroids, however, the collagen fibrils were
arranged in large tangles, and were very loosely packed together.
The tangled collagen masses constituted most of the fibroid tumors,
and they contained little other uterine tissue. Fibroid tumors also
appear to secrete substances that promote the formation of abnormal
collagen mats outside the tumors.
Dr. Leppert noted that, unlike normal uterine tissue, these abnormal
collagen fibrils are not affected by reproductive hormones. For
this reason, attempting to influence fibroids by halting the production
of reproductive hormones may shrink fibroids slightly, but will
have little other effect.
"Hormone therapy is not enough," Dr. Leppert said.
"It can shrink fibroids somewhat, but it won’t make
them go away."
Dr. Leppert and her colleagues are planning a study that would
test the ability of two drug treatments for uterine fibroids. One
drug would block the formation of collagen, in an attempt to keep
existing fibroids from growing larger. The second drug acts to break
apart collagen fibrils, and would be given in an attempt to shrink
existing fibroids. The study is being planned by Dr. Leppert’s
coauthor on the current paper, James Segars, M.D., of NICHD’s
Pediatric and Reproductive Endocrinology Branch and the Uniformed
Services University of the Health Sciences’ Department of
Obstetrics and Gynecology.
Women interested in volunteering for the new study may call Dr.
Segars at 301-496-5800; FAX number 301-402-0884.
Additional information about fibroids is available from the NICHD
publication, Uterine Fibroids. This publication, along with
other NICHD publications, is available on the NICHD Web site, http://www.nichd.nih.gov,
or from the NICHD Information Resource Center, 1-800-370-2943; e-mail
The NICHD is part of the National Institutes of Health (NIH), the
biomedical research arm of the federal government. NIH is an agency
of the U.S. Department of Health and Human Services.