'Natural' Remedies May Interfere With Clinical Trials
By Steven Reinberg
HealthDay Reporter
Patients in phase 1 cancer trials may be skewing the results if they are
also taking vitamins, herbal preparations, minerals and other dietary
supplements, researchers report.
More than one-third of patients in these trials report taking these
alternative medications, according to a report in the Feb. 10 issue of the
Journal of Clinical Oncology.
Phase 1 trials are designed to test the safety of an experimental drug
and to determine if there are any harmful side effects. Since the
biological activity of herbals and other natural supplements aren't always
known, taking them could mask the effect of the drug under study,
explained lead author Dr. Christopher Daugherty, an associate professor
of medicine at the University of Chicago.
"If anything bad happens to a patient in a phase 1 trial, we attribute it to
the experimental drug," Daugherty said. "But much of biologically active
complementary and alternative medicines are agents that have not been
well studied, and we don't know what their effects are in the body by
themselves, let alone when they're combined with experimental drugs,"
he said.
"If we don't know what the effects of a alternative drug are, or if we
don't know the patient is taking it, we can falsely assume that the
experimental drug is unsafe or even safe," Daugherty said.
In the study, Daugherty's team interviewed 212 patients with advanced
cancer enrolled in phase 1 clinical trials. Patients were interviewed about
their use of biologically-based alternative medications.
The team found that 34 percent of patients were taking these
supplements, similar to their usage in the general U.S. population.
Among the patients, 41 said they were taking vitamins and minerals,
such as vitamins A, C, D, E, and B12, selenium, magnesium, zinc, and
copper. In addition, 40 patients said they took herbal preparations,
including cat's claw, laetrile, St. John's wort, milk thistle, ginseng, and
echinacea.
Although patients in phase 1 trials are not supposed to be taking other
drugs, Daugherty believes that there are several reasons why the
natural concoctions are often overlooked.
Sometimes, patients are reluctant to tell the doctor they are taking
alternative medicines, either because they don't think it's important, or
they don't want to be told to stop taking them, Daugherty said.
"Patients need to tell their doctor what medications they are taking, such
as mega-doses of vitamins. These, by themselves, may do no harm, but
if you combine it with other drugs that are metabolized in the liver, who
knows what might happen," he said.
For example, St. John's wort can be toxic to the liver if it is taken along
with certain chemotherapy drugs, Daugherty said. "On the other hand,
some alternative medications may be protective against side effects. So,
we may falsely assume that the experiment's drug is safe," he said.
Doctors too are often lax in asking their patients about alternative
medicines. There may be several reasons for this, Daugherty said. On
the one hand, doctors might not think to ask, and, on the other hand,
they might not think the drug could cause a problem.
And, since it's often difficult to get cancer patients to take part in phase
1 trials, some researchers may be reluctant to turn any potential patient
away. "In addition, most doctors don't know very much about alternative
medicine," Daugherty said.
One expert believes that both patients and doctors need to be concerned
about any medications participants are taking before they start a clinical
trial.
"If people aren't being asked about alternative medications in this day
and age -- that's a bad thing," said Dr. Tieraona Low Dog, the director of
education at the program in integrative medicine at the University of
Arizona.
Patients do need to be asked about alternative medications, because
they can alter results, Low Dog said.
"If you are going to participate in a clinical trial, you have to be
completely candid with the physicians and the researchers about what
you have been using, and that's not just vitamins, minerals and herbs,
that's also over-the-counter medications. Many of these things can affect
the trial medication and your outcome," Low Dog said.
In addition, since alternative medicines are so common today, doctors
need to specifically quiz their patients about them, Low Dog said. "If you
don't ask, they won't tell."
Herbal News