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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.
Depending on the type and purpose of
the trial, the benefits and risks vary significantly. The following table summarizes
possible benefits and risks that patients should carefully consider before enrolling in a
clinical trial.
| Possible Benefits of Trials |
Possible Risks of Trials |
- having access to potentially more
effective therapies than those currently available
- receiving quality medical care from
leading physicians
- being closely monitored for possible
negative effects
- sometimes receiving treatment at a
reduced rate or free of charge
- helping to further new research that may
result in significant medical advances
- for patients in cancer therapy trials
assigned to control groups, they still receive the top standard therapy available today
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- patients may not receive the therapy
under investigation (may receive a placebo—inactive pill—instead)
- the new therapy may not be more
effective than the standard, thoroughly tested therapy
- in Phase I trials, not knowing the
safety consequences of the new therapy (risk is less in Phase III trials)
- new therapy may have unexpected,
possibly severe side effects or may be less effective than standard of care
- insurance companies may not cover all
costs of clinical trials
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What
Should Patients Know Before Entering a Clinical Trial?
Patients interested in participating in
clinical trials should ask their physicians to thoroughly explain the trial, including its
risks and benefits. Patients should learn:
- The purpose of the trial
- How many people will participate
- What type of tests and treatments
patients must undergo
- How long the trial will last
- The potential side effects of tests or
treatments
- What type of long-term follow-up care is
provided
- Whether patients will have to cover any
costs of the trial. If so, whether the patient’s insurance cover the costs or if
financial aid is available
The following terms may be helpful to
patients who are considering participating in clinical trials:
| Protocol |
The
planned course of action for the clinical trial. The protocol is established prior to the
start of the trial and states the number of participants, eligibility requirements, agents
that will be used, dosages, duration, how data is collected, etc. |
| Investigator |
A
researcher in a clinical trial. |
| Sponsor |
The
party or parties responsible for funding the clinical trial. |
| Institutional
Review Board (IRB) |
An
independent board of scientists, physicians, and nurses who review the clinical trial
protocol to ensure patient safety. |
| Informed
consent |
A
patient’s decision to participate in the clinical trial after being informed of the
potential benefits and risks of participation. Participants may withdraw their consent at
any time and leave the trial. |
| Double
blind |
Term
used to describe a clinical trial in which neither the patient nor the researcher knows
which agents are being administered to which patients. This helps prevent bias. |
| Intervention
group |
The
group of participants receiving the new preventive or treatment agent that is being
evaluated in the clinical trial. |
| Control
group |
The
group of participants receiving a standard treatment or placebo (see below) that is being
compared to the new agent in the clinical trial. |
| Randomization |
Assigning
participants by chance to either the intervention group or the control group.
Randomization is often done with a computer. |
| Placebo |
An
inactive substance that may be given to participants in a clinical trial. Sometimes called
a sugar pill. |
| Follow-up |
Monitoring
of participants for a specified time after the clinical trial is completed. |
| Prospective
study |
A
study of a group of patients that is conducted as they are undergoing a treatment or
preventive measure. |
| Retrospective
study |
A
study of a group of patients after they have already undergone a treatment or preventive
measure. "Recall bias," unintentional inaccurate reporting of certain
information, can sometimes influence a retrospective study. |
Directory of Online
Clinical Trial Listings
Updated: June 28, 2007
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