TUESDAY, Feb. 15 (HealthDay News) -- People who take drugs
called bisphosphonates to prevent bone loss may also reduce their
risk of developing colorectal cancer by almost 60 percent compared
to those not on the drugs, a new study suggests.
Bisphosphonates include such common drugs as Fosamax
(alendronate), Boniva (ibandronate), Actonel (risedronate) and
Reclast (zoledronic acid). These drugs work by increasing bone
thickness, thereby reducing the risk of fractures, the researchers
In prior studies, bisphosphonates have already been shown to be
associated with a reduced odds for breast cancer.
"These [new] findings are meaningful because they point to a possible protective effect of this class of drugs being relevant to prevention of many different cancers," said lead researcher Dr. Gad Rennert, from the Technion-Israel Institute of Technology Faculty of Medicine and chairman of the department of community medicine and epidemiology at the Carmel Medical Center of Clalit Health Services in Haifa, Israel.
"This is [similar] to the effect that we and others have shown for [cholesterol-lowering] statins," he said, noting that "bisphosphonates and statins share the same metabolic pathway."
The results of the U.S. National Cancer Institute-supported
study are published in the Feb. 14 issue of the
Journal of Clinical Oncology.
For the study, Rennert's team collected data on almost 1,900
postmenopausal women who took part in the Molecular Epidemiology of
Colorectal Cancer study, which is a population-based trial in
The researchers found that taking bisphosphonates, mostly
Fosamax, for at least a year was associated with a significant 59
percent reduction in relative risk for colorectal cancer.
"The magnitude of the reduced risk is less important because this is an association study; however, it is very significant after controlling for a dozen other known risk factors," Rennert said.
They took into account factors such as family history, ethnic
background, diet, physical activity, weight, vitamin D consumption
and the use of other drugs such as aspirin, statins and hormone
The findings in this study show that bisphosphonates are
associated with a reduced risk of developing colorectal cancer, but
they cannot confirm a causal effect -- that is, the study doesn't
prove that the use of bisphosphonates is responsible for the lower
risk of colorectal cancer.
However, the lowered risk of colorectal cancer seen with
bisphosphonates may be due to the way the drug acts in the body,
which is similar to how cholesterol-lowering drugs called statins
work, according to Rennert. These same researchers also found in
another study that statin use also reduced the risk of colorectal
cancer, he noted.
"We also found a similar effect last year with risk of breast cancer, which has already been replicated by three other groups," Rennert added.
A randomized trial is need to prove that bisphosphonates are
protective against colorectal cancer, Rennert said. "It should be
relatively easy, as it seems that all that is needed is a year of
treatment to see the effect," he said.
The researchers noted, however, that the risks of using
bisphosphonates include the possibility, in rare cases, of
osteonecrosis of the jaw (destruction of the jawbone or jaw
tissue). Bisphosphonates used for osteoporosis have also been
linked to a rare fracture of the thigh, according to the U.S. Food
and Drug Administration.
"The adverse effects profile is of major importance if bisphosphonates are going to be recommended for cancer prevention in healthy people," the study authors cautioned.
Commenting on the study, Eric Jacobs, Strategic Director of
Pharmacoepidemiology at the American Cancer Society, said that "the
lower risk of colorectal cancer risk seen among bisphosphonate
users in this study is intriguing."
However, these results should be interpreted with caution and
require confirmation by additional studies, he said. "Results from
the only other study of bisphosphonate use and colorectal cancer, a
recent large study from the United Kingdom, do not support an
important protective effect," Jacobs noted.
Fortunately, there are other proven ways to help lower risk of
colorectal cancer, he said. "In particular, all Americans, 50 or
older, should get a screening test so that precancerous polyps can
be detected and removed before they turn into cancer."
For more information on colon cancer, visit the
American Cancer Society.
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