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What are Clinical Trials
and Why are They Important?
A clinical trial is an organized
research study designed to investigate new methods of preventing, detecting, diagnosing,
or treating an illness or disease, such as cancer. In some instances, clinical trials
attempt to improve a patient’s quality of life. When studying cancer treatment,
researchers generally attempt to determine whether a new method of treatment is superior
to the standard (currently approved) treatment of the ailment.
Clinical trials are extremely important
in discovering new techniques to fight disease. For example, many of the advances in
breast cancer detection and treatment resulted from clinical trials. These advances
include:
Despite the importance of clinical
trials to both patients and researchers, a recent survey by the American Society of
Clinical Oncology (ASCO) shows that only 2% to 3% of adult patients participate in
clinical trials. Comparatively, 60% to 70% of children with cancer are enrolled in trials.
Of the 6,000 cancer adult patients surveyed by the ASCO, 84% said they were unaware of
trials or unsure they would qualify for participation in a trial. Other reasons for low
participation include the concern about medical costs, fear that treatment would not be
adequate, and the concern of traveling long distances for treatment.
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A current clinical trial is
investigating whether the drug raloxifene (left) is as effective as tamoxifen (right) at
preventing breast cancer in high-risk women. The STAR trial is still enrolling
post-menopausal women in the U.S., Canada, and Puerto Rico. Click here
to learn more about the STAR trial. |
How are Clinical Trials
Planned, Approved and Conducted?
Before a new type of examination or
treatment is approved by the U.S. Food and Drug Administration (FDA) for general use in
the United States, it must first be evaluated in clinical trials. Clinical trials are
typically conducted at universities, cancer centers, hospitals, or clinics. Before a
clinical trial may be conducted, the proposed trial must be reviewed by an Institutional
Review Board (IRB). An IRB is a separate board of scientists, physicians, and nurses who
are not associated with the clinical trial. Once approved by the board, the trial is
closely monitored by the IRB and given a formal review each year (or other interval
depending on the length of the trial). Click here to learn
more about the U.S. drug approval process.
Researchers for each clinical trial
follow an accepted protocol—a planned course of action. For cancer treatment, the
protocol includes dosage levels, frequency, and duration of treatment. Protocols also
establish the frequency and type of laboratory work or other tests needed to assess a
patient’s progress. Clinical trials for cancer treatment may have one, two, three, or
four different treatment plans. Usually, participants in trials with more than one
treatment plan are randomly selected to receive one of the plans. Many clinical trials are
double blind; neither the patient nor the researcher knows what type of treatment is being
administered to a given patient. Double blind studies allow researchers to clearly see
what the true benefits and side effects of a drug or treatment may be without the
influence of other factors.
Before entering a clinical trial, the
patient must give his or her informed consent. This means that the researchers must
explain the protocol and goal of the clinical trial and inform the patient of possible
benefits and risks of participation. A patient may then freely decide whether to
participate in the trial. Clinical trials are not binding; patients may leave at any time.
What are the Different
Types ("Phases") of Clinical Trials?
There are several different types of
clinical trials:
Phase I trials usually test a
new type of cancer treatment and are only given to a small number of participants. The
purpose of a Phase I trial is to learn how to administer a treatment safely. Researchers
will closely monitor the participants’ side effects and adjust dosages if need be.
Phase II trials attempt to
determine patients’ responses to treatments. Typically 30 to 40 people participate in
Phase II trials. In Phase II cancer treatment trials, participants are closely monitored
to see if their cancerous tumors shrink during treatment. If a patient’s tumor
shrink, it is responsive to treatment. If at least one-fifth of the participants
"respond" to treatment, the treatment is considered successful. Researchers of
Phase II trials also monitor side effects. If enough patients respond to therapy, the
trial moves to Phase III.
Phase III trials enroll a large
number of participants (sometimes thousands). Patients are usually divided into groups:
one group receives standard therapy (control group) and the other group receives the new
therapy. For example, the STAR clinical trial (Study of Tamoxifen and
Raloxifene) is a Phase III trial that is enrolling 22,000 post-menopausal women 35 years
of age or older who are at increased risk for developing breast cancer. The STAR Trial
will compare the long-term safety of using the drugs tamoxifen and raloxifene to prevent
breast cancer. As with Phase I and Phase II trials, Phase III participants are closely
monitored for potentially dangerous side effects. If side effects become too severe, the
trial may be canceled.
| Category |
# of Participants |
Purpose |
| Phase I |
Less
than 10 |
tests
how to administer a new therapy, exam, or preventive option |
| Phase II |
30-40 |
tests
patient responses to a new therapy, exam, or preventive option |
| Phase III |
100-1000+ |
compares
new therapy exam or preventive option to a standard one |
| Phase
IV |
varies |
For
marketing purposes, to compare the effectiveness of two therapies already on the market or
to study new uses of therapies |
| Adjuvant |
varies |
For
cancer patients, determines if additional therapy will reduce chances of recurrent cancer. |
Phase IV trials may be conducted for
marketing purposes after a treatment has already been approved by the FDA. These trials vary
in the number of participants and typically compare two treatments that are approved for similar
uses to determine which one is more effective. For example, after the breast cancer drug
tamoxifen was FDA approved to treat advanced breast cancer, researchers investigated whether it
could also prevent breast cancer in women at high risk for the disease (tamoxifen was later FDA
approved for this use too). Phase IV trials may also be conducted to study new uses or the cost
effectiveness of FDA-approved treatments.
Another type of clinical
trial, an adjuvant trial, attempts to determine whether additional therapy will help
eliminate the possibility of a recurrence of cancer in patients at high risk of recurrence
after surgery. For example, chemotherapy is found to help prevent
breast cancer recurrence in many women in conjunction with breast surgery. If an adjuvant
therapy is found beneficial in the trial, it may become standard treatment.
CONTINUED
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