Taking Part in Clinical Trials:
Cancer Prevention Studies
What Participants
Need To Know
N ATION AL INSTITUTES OF HEAL TH
National Cancer Institute

Cancer affects us all --
whether we have the disease,
have had it,
care about someone with it,
or worry about getting it.
Cancer prevention studies
add to knowledge and
progress against cancer.

Introduction
You may have asked for, or been given, this booklet
because you have a higher risk for a certain type of cancer
than most people, or you may want to learn about ways to
prevent cancer. There are two types of prevention clinical
trials that study ways to reduce the risk of getting cancer:
·
Action studies (doing something) -- These focus on
finding out whether actions people take, such as getting
more exercise or quitting smoking, can prevent cancer.
·
Agent studies (taking something) -- These studies
(also called chemoprevention studies) focus on learning
whether taking certain medicines, vitamins, minerals, or
food supplements can prevent cancer.
This booklet is for people who want to learn more about
agent studies designed to prevent cancer. When "cancer
prevention trials or studies" are mentioned in this booklet,
they refer only to agent studies. If you want to learn more
about other types of clinical trials, including other types
of prevention studies, the resources listed on page 23 and 24
can help you.
The booklet explains what prevention clinical trials are,
how they work, and why they're done. This can help read-
ers decide whether taking part in a cancer prevention clini-
cal trial is right for them. Words that appear in bold on
pages 1 to 22 are defined in the Glossary that begins on
page 25.
1

What Is Cancer?
Cancer occurs when, for unknown reasons, cells divide
without control or order. All parts of the body are made up
of cells that normally divide to produce more cells only
when the body needs them. When cancer occurs, cells keep
dividing even when new cells are not needed. The change
from normal to cancerous cells requires several separate, dif-
ferent gene alterations. Eventually uncontrolled growth
from altered genes may produce a tumor that can be
benign (not cancer) or malignant (cancer). Malignant
tumors can invade, damage, and destroy nearby tissues
and spread to other parts of the body. A benign tumor
won't spread to other parts of the body, but local tissue may
be damaged and the growth may need to be removed.
What Are Cancer Risk
Factors?
A cancer risk factor may mean you have an increased
chance to develop cancer. It doesn't mean that you will
develop cancer. Some people have a greater than average
chance to get a certain cancer because they have one or
more risk factors.
Doctors are still learning the role of risk factors in
different cancers. Some risk factors make it very likely
that a person will develop cancer; others seem to increase
a person's risk only slightly.
Risk factors fall into four broad groups and can overlap.
For some cancers, different types of risk factors can work
together to increase cancer risk.
2

1. Lifestyle or behavioral risk factors.
These are things people do that make it more likely
that they will develop cancer. For example, smoking is
strongly linked to lung cancer and a type of sunlight
rays (ultraviolet, or U.V., rays) are linked to
melanoma, a form of skin cancer.
Lifestyle factors can also reduce cancer risk, such as
eating plenty of fruits, vegetables, and fiber to lower
the risk for cancer of the colon and rectum.
2. Hereditary risk factors.
There are altered or changed genes that are passed on from
parent to child, making a person more likely to get cancer.
For example, changes in two genes -- BRCA1 and BRCA2
-- can make a person more likely to get breast cancer.
If you know that one type of cancer seems to run in
your family, you may wish to speak with a trained
genetic counselor. The counselor can answer many of
your questions about cancer risk. You also may be able
to get a test to see if you were born with a higher risk for
getting cancer. Some people worry about how they'll
feel if they learn they have a higher risk for cancer,
especially if there's no method available to reduce their
risk. Other people want to know, no matter what.
To find out more about gene testing, read Understanding
Gene Testing. You can call the National Cancer Institute's
(NCI) Cancer Information Service at 1-800-4-CANCER to
get a copy of this booklet and other information about
gene testing and counseling.
3

3. Environmental risk factors.
There are agents such as asbestos and radon that are
linked with a higher cancer risk (an increased risk for
cancer). People are sometimes exposed to cancer-
causing agents in their workplace.
4. Medical risk factors.
Certain health conditions may increase a person's risk
for some cancers, for example:
·
colon polyps -- abnormal growth of tissue in the
lining of the bowel.
·
previous cancer -- having had radiation or
chemotherapy treatment for illness, such as breast
cancer, may put you at higher risk for the same
type of cancer to return or to get a different type
of cancer.
If a person has one or more of these risk factors, he or
she may want to know more about cancer prevention trials.
If you think you may be at risk for getting cancer, you can
find out whether or not you are eligible to join a cancer
prevention study. (See the section on page 11 -- Who Can
Participate?)
4

What Is a Cancer Prevention
Clinical Trial?
What Is a Clinical Trial?
Clinical trials, also known as clinical studies, are
research studies in which people help doctors find ways
to improve health and health care. Many of today's treat-
ments for cancer are based on the results of past clinical
trials. Examples include clinical studies to treat or prevent
breast and childhood cancers. Because of progress made
through clinical trials, many people treated for cancer are
now living longer.
In cancer prevention trials, people take medicines,
vitamins, minerals or other supplements that doctors
believe may lower the risk of a certain type of cancer.
Scientists who conduct these studies want to learn:
s Does the medicine or supplement (often called a study
agent) prevent cancer?
s How safe is it to take the study agent?
5

How Are Cancer Prevention Clinical
Trials Different From Other Cancer
Studies?
There are different types of cancer clinical trials or
studies. They include:
s chemoprevention trials designed to help people who
have not previously had cancer;
s chemoprevention trials designed to prevent a new type of
cancer from developing in people who have had cancer;
s early detection trials to find cancer, especially in its early
stages;
s treatment trials to test new treatments in people who
have cancer; and
s quality of life studies to improve comfort and quality
of life for people who have cancer.
Some studies, such as treatment clinical trials and
quality-of-life studies, are for people who already have
cancer. Certain chemoprevention trials are for people who
are cancer survivors who want to lower their risk for getting
another cancer. This booklet describes cancer prevention
trials or studies for people who haven't had cancer. People
in these trials are usually healthy people who want to lower
their risk for the disease.
6

How Do Researchers Design
Cancer Prevention Clinical
Trials?
A cancer prevention clinical trial that involves people
results from a long and careful research process. As with
other types of trials, each step, or phase, answers different
questions about the study agent which can be a medicine,
vitamin, mineral, food supplement, or a combination of
these.
s Phase I trials are the first step in testing a prevention
agent in people. Doctors try to find the best way to give
the study agent (for example, by mouth), the best dose,
and if there are any harmful side effects.
s Phase II trials focus on learning whether the agent has a
biologic effect in preventing cancer.
s Phase III trials compare a promising new agent to the
standard one or to no agent, using two groups of people:
·
The intervention group -- This is the group tak-
ing the study agent.
·
The control group -- This group takes either:
1. a standard agent that's being compared with the
study agent;
2. a look-alike pill that contains no active ingre-
dient, called a placebo.
Because less is known about possible risks and benefits
in Phase I and II, these trials usually include only a small
number of participants. In most cases, studies move into
7

Phase III testing only after an agent shows promise in
Phases I and II. Phase III trials may include hundreds of
research centers around the country and hundreds or thou-
sands of people.
Clinical trials follow strict guidelines for science and
ethics. These guidelines deal with many areas, including
the study's design and who can be in the study. Every trial
has a chief investigator, who is usually a doctor. The
investigator prepares a study action plan, called a protocol.
This plan explains what the trial will do, how, and why. For
example, it states:
s How many people will be in the study.
s Who is able to be in the study.
s What study agents people will take.
s What medical tests they will have and how often.
s What information will be gathered.
Every research center that takes part in the trial uses
the same protocol. This ensures that information from all
centers can be combined.
8

How Do Review Groups
Protect Participants?
Clinical trials have several procedures to protect the safe-
ty of the people who join the study. Several groups have to
approve the protocol for every study. Two of those groups
are the sponsor of the study (for example, the National
Cancer Institute) and the Institutional Review Board
(IRB).
Every study center has an IRB, which includes doctors,
other health care providers, consumers, and sometimes
members of the clergy who do not have any personal inter-
est in the results of the study which would bias them.
They serve as neutral reviewers and ensure that the study is
managed fairly and that no one is likely to be harmed who
may decide to join. Each Phase III cancer prevention study
also has a special group called a Data Safety and Moni-
toring Committee that looks at the test results and moni-
tors the safety of the participants, and decides whether the
study should go forward as originally planned.
9

What Happens in a Phase III
Cancer Prevention Clinical
Trial?
If you decide to join a Phase III cancer prevention trial,
you'll work with a research team. Team members may
include doctors, nurses, social workers, and other health care
providers. They will give you clear instructions. You may be
asked to take a medication. You also may be asked to keep a
diary or answer questions about how you're feeling.
During the study, a research team will review your
health carefully. (This means that you may have more tests
and doctor visits than you would if you weren't in the
study.) Team members also may check on you for a while
after the trial ends (followup). To make the trial results as
reliable as possible, it is important for you to follow the
research team's instructions. That means having all doctor
visits and tests, taking medicines on time, and filling out
logs or answering questions. Careful review and followup
help you and scientists find out quickly what agent is best
for reducing cancer risk.
10

Who Can Participate?
Clinical trials try to enroll people who are alike in
certain ways, depending on the study's purpose. Every
protocol tells who can join that study and spells out the
characteristics that people should have. These are called
eligibility criteria. They may include age, gender,
general health, and cancer risk factors.
Eligibility criteria are a key part of medical research.
They help produce results we can trust. And after those
results are known, the information can help doctors find
out who will be helped by the approach being studied if it's
shown to work. For example, a new drug may work for
people with one type of risk factor but not for another, or it
may work better for men than for women.
Eligibility criteria also help protect you. They help make
sure that if you are likely to be harmed by something in the
study design, you are not exposed to that risk.
11

How Are Participants Assigned to
Groups?
Doctors use a process called
randomization (chance)
INTERVENTION
CONTROL
using a computer to assign
you to either the intervention
group or the control group in
Phase III studies. This method
ensures that certain factors
and human choices don't
affect study results, making
them less reliable. When groups are compared with each
other, it is clear whether the study agent works or has bad
side effects. This also helps ensure that the findings really
result from the study agent, and not from something else.
Most Phase III cancer prevention studies use a double-
blind research design. This means that neither you nor the
doctors know which people are taking the study agent or
the control agent. Only the researchers at a central office
know. Sometimes a doctor needs to find out if a participant
has taken the study agent. A doctor can find this out, if
needed, by talking with the central office staff.
No one knows whether it is better to be in the interven-
tion or control group until the study is over and the results
are ready. If that were known, there would be no need for
the study. Either group may have good results or problems.
The results help doctors decide whether to advise people to
take the study agent for cancer prevention.
12

What Is Informed Consent?
Informed consent is a process during which you learn
key facts about a clinical study before you decide whether
or not to join. These facts include details about the study
approach and tests you may have, and the benefits and risks
that could result. (See the section on page 15 -- Should I
Take Part in a Cancer Prevention Study?)
The doctor or nurse will give you a form that goes over
key facts. It's called a consent form. If you decide to take
part in the study, you'll be asked to sign this form. You can
take the form home and discuss it with your family, friends,
or others before you make your decision. If you do decide
to join the study, be sure to ask for a copy of the consent
form so you can look it over at any time.
Don't be afraid to ask questions until you get all the
facts you need to decide. This is an important decision,
and you should feel at ease with the choice you make. In
fact, you should feel free to ask the research team questions
at any time.
Informed consent is more than a piece of paper; it's a
process that lasts throughout a study. For example, you
may be told about new risks or other findings from the
study, and asked to sign a new consent form. As always,
the choice to join or to continue is yours.
You Can Leave the Study at Any Time
Informed consent lasts as long as you're in the study. You
can change your mind and leave the study any time you
want--before the study starts or at any time during the
study or follow-up period. If you decide to leave, you'll
have a chance to talk about other prevention options
with your own doctor or with a doctor from the study.
13

WHAT PROTECTIONS DO YOU HAVE?
Before and during a cancer prevention trial, you have
several important rights:
·
Informed consent -- the right to know all you need
to make a thoughtful decision about joining a study.
·
Changing your mind -- the right to leave the study
at any time.
·
Medical monitoring -- the right to have your health
watched throughout the study.
·
Removal from harm -- the right to be taken off the
study if doctors learn that an agent may harm you.
14

Should I Take Part in a
Cancer Prevention Clinical
Trial?
People decide to be part of a cancer prevention clinical
trial for many reasons. For example:
s Some people who have a higher cancer risk join a cancer
prevention trial because they want to take a more active
role in their health care. Also, because study partici-
pants get regular and careful medical attention, some
health problems may be found early.
s Some people feel good about helping medical knowledge
advance. If the study agent turns out to work against
cancer, it may help others. For example, prevention
trials showed that aspirin helps prevent heart attacks,
and now many people take aspirin daily on their
doctor's advice.
Even when they don't lead to new therapies, clinical
trials often answer important questions and help move
research forward.
You need to weigh the benefits and risks for yourself.
The list in the next section may help you do that. You also
may find it useful to talk with family members or friends,
your health care providers, and anyone you know who has
been in a clinical trial.
Remember: You are the only person who can make this
decision, and if you join a clinical trial, you can change
your mind at any time -- even after the study starts.
15

Prevention Clinical Trials: Weighing
the Pros and Cons
Possible Benefits
s If the agent being studied is found to be helpful, you
may be among the first to benefit.
s In a cancer prevention clinical trial, your health is
reviewed with care.
s A cancer prevention clinical trial gives you a chance to
help doctors learn more about cancer prevention and
help others.
Possible Drawbacks
s New agents may have side effects or risks unknown to
the doctors.
s The side effects, and results, of the agent may be worse
than what's now recommended.
s Even if a new agent is helpful, it may not work for you.
s Health insurance and managed care providers don't
always cover all costs in a clinical trial. (To find out
what costs are likely to be covered for you, talk to a
member of the research team or a social worker.)
16

Questions You Should Ask
Finding answers, and making choices, may be hard for
people who are at risk for cancer -- and for those who care
about them. It's important for you to discuss your concerns
and your choices with your doctor and with the staff of any
clinical study that you're thinking of joining.
Ask questions about any issues that concern you. You
need to review your choices.
Tips for Getting Information
When you talk with your doctor or members of the
research team:
·
Take a family member or friend along for support and
for help in asking questions or recording answers.
·
Plan ahead what to ask -- but don't be afraid to ask any
new questions you think of while you're there.
·
Write down your questions in advance, to make sure
you remember to ask them all.
·
Write down the answers -- in this booklet or someplace
else--where you can review them when you want.
·
Bring a tape recorder to make a record of what's said
(even if you write down answers).
17

Here are some questions you may want to
ask about:
The Study
1. What's the purpose of the study?
2. Why do doctors think the approach may work? (For
example, how has it been studied before?)
3. Who will sponsor the study?
4. Who has reviewed and approved it?
5. How are the study results and safety of participants
being checked?
6. How long will the study last?
18

7. What will I have to do if I join?
8. Will I ever know if I'm taking the study agent that's
being studied?
Possible Risks and Benefits
1. What are the short-term benefits for me?
2. What are the long-term benefits for me?
3. What are the short-term risks, such as side effects, for me?
4. What are the long-term risks for me?
5. What other prevention options do people with my risk
for cancer have?
19

6. How do the risks and benefits of this trial compare with
those options?
Your Participation and Care
1. What kinds of therapies, tests, or procedures will I have
during the trial?
2. Will they hurt, and if so, for how long?
3. How do they compare with the care I'd have outside the
trial?
4. How often, and for how long, will I take the study agent
that is being studied?
5. Will I be able to take my regular medications?
6. Where will I have my medical exams?
20

7. Will I be able to see my own doctor?
8. Who will be in charge of my care?
Personal Issues
1. How could being in the study affect my daily life?
2. Can I talk with other people who are in the study?
Cost Issues
1. Will I have to pay for any part of the trial, such as tests
or the study agent?
2. If I will, what are the charges likely to be?
3. What is my health insurance likely to cover?
21

4. Who can help answer any questions from my insurance
company or health plan?
Other Questions
Use this space to write down other questions you have.
Others Can Help
As you make your decisions, remember that there are
resources for people who have a higher risk for cancer.
The resources on page 23 can give you more information
and put you in touch with contacts in your community.
22

National Cancer Institute
Information Resources
If you have questions about cancer prevention clinical
trials, ask your doctor, nurse, or other health provider. It
may be helpful for you to bring this booklet with you to an
office visit. Use the spaces provided to write down informa-
tion you'll want to remember or refer to later.
You may want more information for yourself, your fami-
ly, and your doctor. The following National Cancer
Institute (NCI) services are available to help you.
Telephone...
Cancer Information Service (CIS)
Provides accurate, up-to-date information on cancer to
patients and their families, health professionals, and the
general public. Information specialists translate the latest
scientific information into understandable language and
respond in English, Spanish, or on TTY equipment.
Toll-free: 1-800-4-CANCER (1-800-422-6237)
TTY: 1-800-332-8615
Internet...
These web sites may be useful:
http://www.nci.nih.gov
NCI's primary web site; contains information
about the Institute and its programs.
http://cancerTrials.nci.nih.gov
CancerTrials; NCI's comprehensive clinical trials informa-
tion center for patients, health professionals, and the
23

public. Includes information on understanding trials,
deciding whether to participate in trials, finding specific
trials, plus research news and other resources.
http://cancernet.nci.nih.gov
CancerNetTM ; contains material for health professionals,
patients, and the public, including information from PDQ®
about cancer treatment, screening, prevention, supportive
care, and clinical trials, and CANCERLIT®, a bibliographic
database.
http://rex.nci.nih.gov
Includes news, upcoming events, educational materials, and
publications for patients, the public, and the mass media.
http://chid.nih.gov/ncichid/
Cancer Patient Education Database; provides information
on cancer patient education resources for patients, their
families, and health professionals.
E-mail...
CancerMail
Includes NCI information about cancer treatment, screen-
ing, prevention, and supportive care. To obtain a contents
list, send e-mail to cancermail@icicc.nci.nih.gov with
the word "help" in the body of your message.
Fax...
CancerFax®
Includes NCI information about cancer
treatment, screening, prevention, and supportive care.
To obtain a contents list, dial 301-402-5874 from a fax
machine hand set and follow the recorded instructions.
24

Glossary
Action studies: In cancer prevention clinical trials, stud-
ies that focus on finding out whether actions people take
can prevent cancer.
Agent studies: In cancer prevention clinical trials, studies
that focus on examining whether taking certain medicines,
vitamins, minerals, or food supplements can prevent cancer.
Benign: Not cancerous; cannot invade neighboring tissues
or spread to other parts of the body.
Bias: Having an idea about what the study results will
show before the clinical trial is conducted.
Chemoprevention studies: Also called "cancer preven-
tion agent studies." Cancer prevention studies that test
whether the study agent -- usually medicines, vitamins,
minerals, food supplements, or a combination of them --
can reduce a person's chances of getting cancer.
Clinical trials: Also called "clinical studies." Research
studies with people. Each trial tries to answer specific scien-
tific questions and to find better ways to prevent, detect, or
treat diseases or to improve care.
Colon polyps: Abnormal growths of tissue on the lining
of the bowel. Polyps are a risk factor for cancer of the
bowel.
Consent form: A document that provides key facts about
a clinical trial. This includes information about the study
agent, tests that study participants may have, and possible
benefits and risks. Although all participants in a clinical
trial must sign a consent form, they can leave the study at
any time. As a trial proceeds, there may be new consent
forms.
25

Control group: In a Phase III cancer prevention clinical
trial of a study agent, the group that receives either a
placebo or a standard agent that is being compared to a
new agent.
Data Safety and Monitoring Committee: An impar-
tial group that provides oversight of a clinical trial and
reviews the results to see if they are acceptable. This group
determines if the trial should be altered or closed.
Double-blind: A method used to prevent bias in a clinical
trial. Neither the participants nor the doctor knows who is
taking the study agent and who is not. Only researchers at
a central office know.
Environmental risk factor: A hazardous agent that is
known to cause cancer or increase risk when people are
exposed to it, for example asbestos, radon, and second-hand
smoke.
Followup: Keeping track of the health of people who par-
ticipate in a clinical study for a period of time during the
study and after the study ends.
Gene alterations: Changes in the cells' unit of inheri-
tance that may be good or bad for the body.
Hereditary risk factor: Altered or mutated genes that
make it more likely that a person will develop cancer. Also
called an "inherited" risk factor, but this does not necessarily
have to be inherited from a parent. It can be acquired in a
germline cell through lifestyle behaviors or through expo-
sure to hazards in the environment. Once this cell is
altered, the mutated gene can pass to the next generation.
26

Informed consent: A process in which a person learns
key facts about a clinical trial, including potential risks and
benefits, before deciding whether or not to participate in a
study. Informed consent continues throughout the trial.
Institutional Review Board (IRB): A group of scien-
tists, doctors, clergy, and consumers at each health care
facility that participates in a clinical trial. IRBs are designed
to protect study participants. They review and must
approve the action plan for every clinical trial. They check
to see that the trial is well designed, does not involve undue
risks, and includes safeguards for patients.
Intervention group: The group receiving the study
agent that's being tested in a clinical trial or clinical study.
Investigator: A researcher in a clinical trial or clinical
study.
Lifestyle risk factor: Personal behavior, such as smok-
ing, that may increase a person's risk for cancer. Also called
`behavioral risk factor.'
Malignant: Cancerous. Malignant tumors can invade sur-
rounding tissues and spread to other parts of the body.
Medical risk factor: Health conditions that may lead to
cancer. See colon polyps.
Placebo: A tablet or capsule that looks like the study agent
but doesn't contain any active ingredient. Some people call
a placebo a "sugar pill."
Protocol: An action plan for a clinical trial. The plan
states what the study will do, how, and why. It explains
how many people will be in it, who's eligible to participate,
what study agents they'll take, what tests they'll receive and
how often, and what information is gathered.
27

Randomization: A method used to prevent bias in
research. People are assigned by chance, often by a comput-
er, either to receive the study agent (intervention group) or
not (control group).
Risk factor: A condition that increases a person's chance
of developing a particular disease. Cancer risk factors
include age, lifestyle (including exposure to cancer-causing
substances), family history of cancer, or medical conditions
that can lead to cancer.
Side effects: Problems that occur when a study agent
causes expected but unpleasant conditions, like dry skin or
headaches.
Sponsor: The agency or firm responsible for financing the
clinical trial.
Study agent: A medicine, vitamin, mineral, food supple-
ment, or a combination of them that's being tested in a
cancer prevention trial. A study agent is usually something
that's taken by mouth (eaten or swallowed).
Tissue: Specialized cells arranged in a precise pattern in
the body.
Tumor: An abnormal growth of tissue. Tumors may be
either benign or cancerous.
Ultraviolet: Invisible rays that are part of the energy that
comes from the sun which can burn the skin and cause skin
cancer.
28

Document Outline

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Contents