News> <Alternative [Complementary] Medicine>
<Herbal supplement weakens cancer drug, scientists say St.John's
wort effect last weeks after use stops>
supplement weakens cancer drug, scientists say
St. John's wort effects last weeks after use stops
Chronicle Medical Writer
John's wort apparently blunts the absorption of a common cancer
drug, and the effect lasts weeks after people stop taking the
popular herbal supplement, scientists reported yesterday.
to help mild depression, St. John's wort has already been shown
to interfere with other medications, including the HIV drug indinavir
and cyclosporine, which is used to treat rejection of transplanted
latest research shows that the herbal supplement led to a 40 percent
decrease in blood levels of Camptosar, used to treat many forms
of cancer. Three weeks after patients discontinued St. John's
wort, the blunting effects persisted.
may have drastic consequences on the effectiveness of treatment,"
said Dr. Ron A.H.J. Mathijssen of the Rotterdam Cancer Institute
in the Netherlands, who presented results of his study at the
American Association for Cancer Research meeting being held at
San Francisco's Moscone Center.
study was small, involving just five patients, but doctors are
reluctant to try it in larger groups because they don't want to
put cancer patients at risk. Mathijssen said it appears that St.
John's wort interferes with a metabolic pathway that is used in
as much as 50 percent of all medicines.
John's wort is classified as a dietary supplement, and as such
it is free from most regulation.
are particularly concerned about herbal supplements, because surveys
show that about half of all cancer patients use some form of alternative
medicine. Many don't tell their doctors what they are taking.
they are largely unregulated, it is hard to know exactly how much
active ingredient is contained in any given dose of an herbal
or dietary supplement. Some also have been known to contain contaminants.
Karen Antman, an oncologist at New York Presbyterian Hospital,
noted that it is common for cancer patients to experience depression.
"It may be safer to have them on a drug (for depression) that
we know more about, and we can reliably know what's in the tablet,"
reported at the cancer research meeting yesterday:
Scientists from Harvard University said they have discovered a
protein in blood that is significantly elevated in women with
ovarian cancer. The protein, called haptoglobin, could be used
in future tests to detect this malignancy, which is usually well
advanced by the time it is discovered.
Another protein, RhoC, was found to be helpful in predicting which
small breast tumors are likely to grow into invasive cancer, according
to researchers from the University of Michigan. They said it may
someday be used to help guide treatment decisions.
A fairly common genetic abnormality may play a role in accelerating
the spread of HNSCC (head and neck squamous cell carcinoma). The
mutation involves a gene that codes for a protein involved in
helping cells move and grow, according to scientists at Max Planck
Institute for Biochemistry in Germany. It does not cause cancer,
but is associated with a shorter life span for people with HNSCC
who have it. About 45 to 50 percent of the population carries
at least one copy of the abnormal gene, called FGFR4.
Inducing hypothyroidism -- also known as underactive thyroid --
appears to help extend survival of patients with lethal brain
tumors. Patients who responded to drugs used to treat overactive
thyroids lived an average of 11 months, compared with three months
for the group that did not become hypothyroid. Scientists from
the Cleveland Clinic believe that the regimen helped increase
the effectiveness of the anti-cancer agent tamoxifen.
A drug called Apomine appears to help some people with melanoma.
In a study, researchers at the Arizona Cancer Center in Tucson
said the disease stabilized in two of nine melanoma patients who
were given the drug. The subjects all had invasive cancer that
was resistant to chemotherapy.