Clinical Trials: Questions and Answers
- Clinical trials are research studies that test how well new medical approaches work in people (see Question 1).
- Every clinical trial has a protocol, which describes what will be done in the study, how it will be conducted, and why each part of the study is necessary (see Question 4).
- Informed consent is a process by which people learn the important facts about a clinical trial to help them decide whether to participate (see Question 6).
- Payment of patient care costs in clinical trials varies by health insurance plan and by study (see Question 11).
- What are clinical trials, and why are they important?
Clinical trials are research studies that test how well new medical approaches
work in people. Each study answers scientific questions and tries to find
better ways to prevent, screen for, diagnose, or treat a disease. People who
take part in cancer
clinical trials have an opportunity to contribute to knowledge of, and progress
against, cancer. They also receive up-to-date care from experts.
- What are the types of clinical trials?
There are several types of clinical trials:
Who sponsors clinical trials?
Prevention trials test new approaches, such as medications,
or other supplements,
that doctors believe may lower the risk of developing a certain type of
cancer. Most prevention trials are conducted with healthy people who have
not had cancer. Some trials are conducted with people who have had cancer
and want to prevent recurrence
(return of cancer), or reduce the chance of developing a new type of cancer.
Screening trials study ways to detect cancer earlier.
They are often conducted to determine whether finding cancer before it
decreases the chance of dying from the disease. These trials involve people
who do not have any symptoms of cancer.
trials study tests or procedures that could be used to identify
cancer more accurately. Diagnostic trials usually include people who have
signs or symptoms of cancer.
Treatment trials are conducted with people who have
cancer. They are designed to answer specific questions about, and evaluate
the effectiveness of, a new treatment or a new way of using a standard
treatment. These trials test many types of treatments, such as new
new approaches to surgery
therapy, or new combinations of treatments.
(also called supportive
care) trials explore ways to improve the comfort and quality
of life of cancer patients and cancer survivors. These trials may study
ways to help people who are experiencing nausea,
sleep disorders, depression,
or other effects from cancer or its treatment.
Genetics studies are sometimes part of another cancer
clinical trial. The genetics component of the trial may focus on how genetic
makeup can affect detection, diagnosis,
to cancer treatment.
Population- and family-based genetic research studies differ from traditional
cancer clinical trials. In these studies, researchers look at tissue
samples, generally from families or large groups of people, to find genetic
changes that are associated with cancer. People who participate in genetics
studies may or may not have cancer, depending on the study. The goal of
these studies is to help understand the role of genes
in the development of cancer.
Government agencies, such as the National
Cancer Institute (NCI)
and other parts of the National
Institutes of Health (NIH),
the Department of Defense, and the Department of Veterans Affairs, sponsor
and conduct clinical trials. In addition, organizations or individuals, such
medical institutions, foundations, volunteer groups, and pharmaceutical companies,
also sponsor clinical trials.
NCI sponsors a large number of clinical trials and has a number of programs
designed to make clinical trials widely available in the United States. These
programs include the following:
How are participants protected?
The Cancer Centers Program provides support to research-oriented
institutions, including those that have been designated as NCI Comprehensive
or Clinical Cancer Centers for their scientific excellence. More information
is available in the National Cancer Institute-Designated Cancer Centers
Database, which is available at http://www.cancer.gov/cancertopics/factsheet/NCI/cancer-centers
on the Internet.
The Specialized Programs of Research Excellence (SPOREs) bring
together scientists and researchers to design and implement research programs
that can improve prevention, detection, diagnosis, and treatment of specific
types of cancer. More information about SPOREs is available at http://spores.nci.nih.gov/index.html
on the Internet.
The Clinical Trials Cooperative Group Program brings
researchers, cancer centers, and doctors together into cooperative groups.
These groups work with the NCI to identify important questions in cancer
research, and design and conduct multisite clinical trials to answer these
questions. Cooperative groups are located throughout the United States
and in Canada and Europe. For more information, refer to the fact sheet
NCI's Clinical Trials Cooperative Group Program at http://www.cancer.gov/cancertopics/factsheet/NCI/clinical-trials-cooperative-group
on the Internet.
The Cancer Trials Support Unit (CTSU) makes NCI-sponsored
III treatment trials available to doctors and patients in the United
States and Canada . Doctors who are not affiliated with an NCI-sponsored
Clinical Trials Cooperative Group (see above) must complete an application
process, which includes credential verification and site preparedness
assessment, to become members of the CTSU's National Network of Investigators.
CTSU members can enroll patients in clinical trials through the program's
Web site, which is located at http://www.ctsu.org
on the Internet. General information about the CTSU is also available
on the program's Web site, or by calling 1–888–823–5923.
The Community Clinical Oncology Program (CCOP) makes
clinical trials available in a large number of communities across the
United States. Local hospitals throughout the country affiliate with a
cancer center or a cooperative group. This affiliation allows doctors
to offer people participation in clinical trials more easily, so they
do not have to travel long distances or leave their usual caregivers.
The Minority-Based Community Clinical Oncology Program
focuses on encouraging minority populations to participate in clinical
trials. More information about the CCOP can be found in the NCI fact sheet
Community Clinical Oncology Program: Questions and Answers, which
is available at http://www.cancer.gov/cancertopics/factsheet/NCI/CCOP
on the Internet.
The National Institutes of Health Clinical Center,
a research hospital located in Bethesda, Maryland, is part of the NIH.
Trials at the Clinical Center are conducted by the components of the NIH,
including the NCI. The NCI fact sheet Cancer Clinical Trials at the
National Institutes of Health Clinical Center: Questions and Answers has
more information about the Clinical Center. This fact sheet is available
on the Internet.
Research with people is conducted according to strict scientific and ethical
principles. Every clinical trial has a protocol, or action plan, which acts
like a “recipe” for conducting the trial. The plan describes what
will be done in the study, how it will be conducted, and why each part of
the study is necessary. The same protocol is used by every doctor or research
center taking part in the trial.
All clinical trials that are federally funded or that evaluate a new drug
or medical device subject to Food and Drug Administration regulation must
be reviewed and approved by an Institutional
Review Board (IRB).
Many institutions require that all clinical trials, regardless of funding,
be reviewed and approved by a local IRB. The Board, which includes doctors,
researchers, community leaders, and other members of the community, reviews
the protocol to make sure the study is conducted fairly and participants are
not likely to be harmed. The IRB also decides how often to review the trial
once it has begun. Based on this information, the IRB decides whether the
clinical trial should continue as initially planned and, if not, what changes
should be made. An IRB can stop a clinical trial if the researcher is not
following the protocol or if the trial appears to be causing unexpected harm
to the participants. An IRB can also stop a clinical trial if there is clear
evidence that the new intervention is effective, in order to make it widely
NIH-supported clinical trials require data and safety monitoring. Some clinical
trials, especially phase III clinical trials, use a Data and Safety Monitoring
Board (DSMB). A DSMB is an independent committee made up of statisticians,
physicians, and patient advocates. The DSMB ensures that the risks of participation
are as small as possible, makes sure the data are complete, and stops a trial
if safety concerns arise or when the trial's objectives have been met.
What are eligibility
criteria, and why are they important?
Each study's protocol has guidelines for who can or cannot participate in
the study. These guidelines, called eligibility criteria, describe characteristics
that must be shared by all participants. The criteria differ from study to
study. They may include age, gender, medical history, and current health status.
Eligibility criteria for treatment studies often require that patients have
a particular type and stage
Enrolling participants with similar characteristics helps to ensure that
the results of the trial will be due to what is under study and not other
factors. In this way, eligibility criteria help researchers achieve accurate
and meaningful results. These criteria also minimize the risk of a person's
condition becoming worse by participating in the study.
What is informed consent?
Informed consent is a process by which people learn the important facts about
a clinical trial to help them decide whether to participate. This information
includes details about what is involved, such as the purpose of the study,
the tests and other procedures used in the study, and the possible risks and
benefits. In addition to talking with the doctor or nurse,
people receive a written consent form explaining the study. People who agree
to take part in the study are asked to sign the informed consent form. However,
signing the form does not mean people must stay in the study. People can leave
the study at any time—either before the study starts or at any time
during the study or the follow-up
The informed consent process continues throughout the study. If new benefits,
risks, or side
effects are discovered during the study, the researchers must inform the
participants. They may be asked to sign new consent forms if they want to
stay in the study.
Where do clinical trials take place?
Clinical trials take place in doctors’ offices, cancer centers, other
medical centers, community hospitals and clinics, and veterans’ and
military hospitals in cities and towns across the United States and in other
countries. Clinical trials may include participants at one or two highly specialized
centers, or they may involve hundreds of locations at the same time.
How are clinical trials conducted?
Clinical trials are usually conducted in a series of steps, called phases.
Treatment clinical trials listed in PDQ®,
the NCI's comprehensive cancer information database, are always assigned a
phase. However, screening, prevention, diagnostic, and quality-of-life studies
do not always have a phase. Genetics clinical trials generally do not have
I trials are the first step in testing a new approach in people.
In these studies, researchers evaluate what dose
is safe, how a new agent should be given (by mouth, injected
into a vein, or injected into the muscle), and how often. Researchers watch
closely for any harmful side effects. Phase I trials usually enroll a small
number of patients and take place at only a few locations. The dose of the
or technique is increased a little at a time. The highest dose with an acceptable
level of side effects is determined to be appropriate for further testing.
II trials study the safety and effectiveness of an agent or
intervention, and evaluate how it affects the human body. Phase II studies
usually focus on a particular type of cancer, and include fewer than 100
- Phase III trials compare a new agent or intervention
(or new use of a standard one) with the current standard
therapy. Participants are randomly assigned to the standard group or
the new group, usually by computer. This method, called randomization,
helps to avoid bias
and ensures that human choices or other factors do not affect the study's
results. In most cases, studies move into phase III testing only after they
have shown promise in phases I and II. Phase III trials often include large
numbers of people across the country.
IV trials are conducted to further evaluate the long-term
safety and effectiveness of a treatment. They usually take place after the
treatment has been approved for standard use. Several hundred to several
thousand people may take part in a phase IV study. These studies are less
common than phase I, II, or III trials.
People who participate in a clinical trial work with a research team. Team
members may include doctors, nurses, social
workers, dietitians, and other health professionals. The health care team
provides care, monitors participants’ health, and offers specific instructions
about the study. So that the trial results are as reliable as possible, it
is important for participants to follow the research team's instructions.
The instructions may include keeping logs or answering questionnaires. The
research team may continue to contact participants after the trial ends.
What are some of the benefits of taking part in a clinical trial?
The benefits of participating in a clinical trial include the following:
What are some of the possible risks associated with taking part in a clinical
- Participants have access to promising new approaches that are often not
available outside the clinical trial setting.
- The approach being studied may be more effective than the standard approach.
- Participants receive regular and careful medical attention from a research
team that includes doctors and other health professionals.
- Participants may be the first to benefit from the new method under study.
- Results from the study may help others in the future.
The possible risks of participating in a clinical trial include the following:
Who pays for the patient care costs associated with a
- New drugs or procedures under study are not always better than the standard
care to which they are being compared.
- New treatments may have side effects or risks that doctors do not expect
or that are worse than those resulting from standard care.
- Participants in randomized
trials will not be able to choose the approach they receive.
- Health insurance and managed care providers may not cover all patient
care costs in a study.
- Participants may be required to make more visits to the doctor than they
would if they were not in the clinical trial.
Health insurance and managed care providers often do not cover the patient
care costs associated with a clinical trial. What they cover varies by health
plan and by study. Some health plans do not cover clinical trials if they
consider the approach being studied “experimental”
However, if enough data show that the approach is safe and effective, a health
plan may consider the approach “established” and cover some or
all of the costs. Participants may have difficulty obtaining coverage for
costs associated with prevention and screening clinical trials; health plans
are currently less likely to have review processes in place for these studies.
It may, therefore, be more difficult to get coverage for the costs associated
with them. In many cases, it helps to have someone from the research team
talk about coverage with representatives of the health plan.
Health plans may specify other criteria a trial must meet to be covered.
The trial might have to be sponsored by a specified organization, be judged
“medically necessary” by the health plan, not be significantly
more expensive than treatments the health plan considers standard, or focus
on types of cancer for which no standard treatments are available. In addition,
the facility and medical staff might have to meet the plan's qualifications
for conducting certain procedures, such as bone
marrow transplants. More information about insurance coverage can be found
on the NCI's Clinical Trials and Insurance Coverage: A Resource Guide
Web page at http://www.cancer.gov/clinicaltrials/learning/insurance-coverage
on the Internet.
Many states have passed legislation or developed policies requiring health
plans to cover the costs of certain clinical trials. For more information,
visit the NCI's Web site at http://www.cancer.gov/clinicaltrials/developments/laws-about-clinical-trial-costs
on the Internet.
Federal programs that help pay the costs of care in a clinical trial include
those listed below:
What are some questions people might ask their health care provider before
entering a clinical trial?
Medicare reimburses patient care costs for its beneficiaries who participate
in clinical trials designed to diagnose or treat cancer. Information about
Medicare coverage of clinical trials is available at http://www.medicare.gov
on the Internet, or by calling Medicare's toll-free number for beneficiaries
at 1–800–633–4227 (1–800–MEDICARE). The
toll-free number for the hearing impaired is 1–877–486–2048.
Also, the NCI fact sheet More Choices in Cancer Care: Information
for Beneficiaries on Medicare Coverage of Cancer Clinical Trials
is available at http://www.cancer.gov/cancertopics/factsheet/support/medicare
on the Internet.
Beneficiaries of TRICARE, the Department of Defense's health program,
can be reimbursed for the medical costs of participation in NCI-sponsored
phase II and phase III cancer prevention (including screening and early
detection) and treatment trials. Additional information is available in
the NCI fact sheet TRICARE Beneficiaries Can Enter Clinical Trials
for Cancer Prevention and Treatment Through a Department of Defense and
National Cancer Institute Agreement. This fact sheet can be found
on the Internet.
The Department of Veterans Affairs (VA) allows eligible veterans to
participate in NCI-sponsored prevention, diagnosis, and treatment studies
nationwide. All phases and types of NCI-sponsored trials are included.
The NCI fact sheet The NCI/VA Agreement on Clinical Trials: Questions
and Answers has more information. It is available at http://www.cancer.gov/cancertopics/factsheet/NCI/VA-clinical-trials
on the Internet.
It is important for people to ask questions before deciding to enter a clinical
trial. Questions people might want to ask their doctor or nurse include the
- What is the purpose of the study?
- Why do the researchers think the approach being tested may be effective?
Has it been tested before?
- Who is sponsoring the study?
- Who has reviewed and approved the study?
- What are the medical credentials and experience of the researchers and
other study personnel?
- How are the study results and safety of participants being monitored?
- How long will the study last?
- How will the results be shared?
Possible Risks and Benefits
- What are the possible short-term benefits?
- What are the possible long-term benefits?
- What are the short-term risks, such as side effects?
- What are the possible long-term risks?
- What other treatment options are available?
- How do the possible risks and benefits of the trial compare with those
of other options?
Participation and Care
- What kinds of treatment, medical tests, or procedures will the participants
have during the study? How often will they receive the treatments, tests,
- Will treatments, tests, or procedures be painful? If so, how can the
pain be controlled?
- How do the tests in the study compare with what people might receive
outside the study?
- Will participants be able to take their regular medications while in
the clinical trial?
- Where will the participants receive their medical care? Will they be
in a hospital? If so, for how long?
- Who will be in charge of the participants’ care? Will they be able
to see their own doctors?
- How long will participants need to stay in the study? Will there be follow-up
visits after the study?
- How could being in the study affect the participants’ daily lives?
- What support is available for participants and their families?
- Can potential participants talk with people already enrolled in the study?
What happens when a clinical trial is over?
- Will participants have to pay for any treatment, tests, or other charges?
If so, what will the approximate charges be?
- What is health insurance likely to cover?
- Who can help answer questions from the insurance company or health plan?
After a clinical trial is completed, the researchers look carefully at the
data collected during the trial before making decisions about the meaning
of the findings and further testing. After a phase I or II trial, the researchers
decide whether to move on to the next phase, or stop testing the agent or
intervention because it was not safe or effective. When a phase III trial
is completed, the researchers look at the data and decide whether the results
have medical importance.
The results of clinical trials are often published in peer-reviewed, scientific
journals. Peer review is a process by which experts review the report before
it is published to make sure the analysis and conclusions are sound. If the
results are particularly important, they may be featured by the media and
discussed at scientific meetings and by patient advocacy groups before they
are published. Once a new approach has been proven safe and effective in a
clinical trial, it may become standard practice. (Standard practice is a currently
accepted and widely used approach.)
The National Library of Medicine's Web site offers links to resources for
finding the results of clinical trials. It includes information about published
and unpublished results. This resource can be found at http://www.nlm.nih.gov/services/ctresults.html
on the Internet.
Where can people find more information about clinical trials?
In addition to the resources described in Question 3, people interested
in taking part in a clinical trial should talk with their health care provider.
Information about cancer clinical trials is also available from the NCI's
Information Service (CIS).
Information specialists at the CIS use PDQ to identify and provide detailed
information about specific ongoing clinical trials. PDQ includes all NCI-funded
clinical trials and some studies conducted by independent investigators at
hospitals and medical centers in the United States and Europe.
People also have the option of searching for clinical trials on their own.
The clinical trials page of the NCI's Web site, located at http://www.cancer.gov/clinicaltrials/
on the Internet, provides information about clinical trials and links to PDQ.
Another resource is the NIH's ClinicalTrials.gov Web site. ClinicalTrials.gov
lists clinical trials sponsored by the NIH, other Federal agencies, and the
pharmaceutical industry for a wide range of diseases, including cancer and
other conditions. This site can be found at http://clinicaltrials.gov
on the Internet.
# # #
Related NCI materials and Web pages:
For more help, contact:
- NCI's Cancer Information Service
(toll-free): 18004CANCER (18004226237)
LiveHelp® online chat: https://cissecure.nci.nih.gov/livehelp/welcome.asp
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