Studies: Bone Drugs May Help Prevent Breast Cancer
From Associated Press (December 10, 2009)
SAN ANTONIO--New results from a landmark women's health study raise
the exciting possibility that bone-building drugs such as
Fosamax and Actonel
may help prevent breast cancer.
Women who already were using these medicines when the study began
were about one-third less likely to develop invasive breast cancer
over the next seven years than women not taking such pills, doctors
reported Thursday.
The study is not enough to prove that these drugs, called
bisphosphonates, prevent cancer. More definitive studies should
give a clearer answer in a year or two.
Yet it greatly amplifies the hopeful buzz that started last year
when researchers reported that a bisphosphonate cut the chances
that cancer would come back in women already treated for the
disease.
"Now we're actually looking at this in the general population --
healthy women who have never had breast cancer. And it looks like
it's protective in those women as well," said Dr. Peter Ravdin of
the University of Texas Health Science Center at San Antonio.
"There's a strengthening story here," said Ravdin, who helped
review the research for the San Antonio Breast Cancer Symposium,
where results were reported Thursday. "This is very
promising."
Millions of women already take bisphosphonates for bone-thinning
osteoporosis, or to prevent fractures from cancer that has spread
to their bones.
The drugs range in cost from $100 for a three-month supply of the
generic version of Merck & Co. Inc.'s Fosamax pills to as much
as $1,200 for an infusion of Novartis AG's Zometa, given every six
months for osteoporosis. Other brands are e
GlaxoSmithKline PLC's
Boniva and Warner
Chilcott PLC's Actonel
.
After last year's surprise finding that Zometa
cut the risk of cancer recurrence, doctors
wondered: Is it just making bones more resistant to cancer's
spread, or does it have wider anti-tumor effects that may prevent
cancer from developing in the first place?
Dr. Rowan Chlebowski of Los Angeles Biomedical Research Institute
at Harbor-UCLA Medical Center in Torrance, Calif., sought answers
from the Women's Health Initiative, a federally funded study best
known for revealing previously unrecognized risks from estrogen and
progestin pills after menopause.
Of the 151,592 participants, 2,216 were taking bisphosphonates --
mostly Fosamax -- when the study began. About seven years later, 31
percent fewer invasive breast cancer cases had occurred among those
women than the others. The benefit persisted even after researchers
took into account differences in age, smoking, weight, hormone and
vitamin D use, and other things that affect bone density and breast
cancer risk.
However, women taking bisphosphonates were more likely to develop a
noninvasive tumor of the milk duct called DCIS. Chlebowski contends
this is an acceptable trade-off: For every 1,000 women taking a
bisphosphonate for one year, one fewer case of invasive,
life-threatening breast cancer would occur.
Overall, the results suggest that bisphosphonates have direct
anti-cancer effects and are not just helping bones resist cancer's
spread.
"If it only worked in the bone marrow then you wouldn't be
influencing incidence" of new cancers, said Chlebowski, who has
consulted for makers of bisphosphonates and other cancer prevention
drugs.
A second study supported that view. Dr. Gad Rennert of the
Technion-Israel Institute of Technology in Haifa, Israel, compared
about 2,000 postmenopausal women with breast cancer to 2,000
similar women without the disease. Those with cancer were 29
percent less likely to have been taking bisphosphonates, he
found.
Neither study collected information on side effects.
Bisphosphonates can cause bone, joint or muscle pain and in rare
cases, jawbone decay.
"These are drugs that, generally speaking, are relatively well
tolerated" and fairly safe, but they still should not be taken for
cancer prevention until more definitive studies show their risks
and benefits, said Dr. Eric Winer of the Dana-Farber Cancer Center
in Boston. He has no financial ties to any makers of these
drugs.
The only drugs approved now for preventing breast cancer in healthy
women at higher risk are the hormone blockers
tamoxifen and raloxifene
. Side effects such as hot flashes, high blood
pressure and a higher risk of blood clots have limited their
use.
The cancer conference is sponsored by the American Association for
Cancer Research, Baylor College of Medicine and the UT Health
Science Center.
------
On the Net:
Patient information: http://www.cancer.net
American Cancer Society: http://www.cancer.org
Cancer conference: http://www.sabcs.org
Posted: December 2009
