What is a Clinical Trial?
Clinical trials are research studies in which people help doctors find ways to improve health and cancer care. Each study tries to answer scientific questions and to find better ways to prevent, diagnose, or treat cancer.
Why are there clinical trials?
A clinical trial is one of the final stages of a long and careful cancer research process. Studies are done with cancer patients to find out whether promising approaches to cancer prevention, diagnosis, and treatment are safe and effective.
What are the different types of clinical trials?
What are the phases of clinical trials?
Most clinical research that involves the testing of a new drug progresses in an orderly series of steps, called phases. This allows researchers to ask and answer questions in a way that results in reliable information about the drug and protects the patients. Most clinical trials are classified into one of three phases:
- Phase I trials: These first studies in people evaluate how a new drug should be given (by mouth, injected into the blood, or injected into the muscle), how often, and what dose is safe. A phase I trial usually enrolls only a small number of patients, sometimes as few as a dozen.
- Phase II trials: A phase II trial continues to test the safety of the drug, and begins to evaluate how well the new drug works. Phase II studies usually focus on a particular type of cancer.
- Phase III trials: These studies test a new drug, a new combination of drugs, or a new surgical procedure in comparison to the current standard. A participant will usually be assigned to the standard group or the new group at random (called randomization). Phase III trials often enroll large numbers of people and may be conducted at many doctors' offices, clinics, and cancer centers nationwide
In addition, after a treatment has been approved and is being marketed, the drug's maker may study it further in a phase IV trial. The purpose of phase IV trials is to evaluate the side effects, risks, and benefits of a drug over a longer period of time and in a larger number of people than in phase III clinical trials. Thousands of people are involved in a phase IV trial
Should I Take Part in a Clinical Trial?
Only you can make the decision about whether or not to participate in a clinical trial. Before you make your decision, you might do the following.
- Learn as much as possible about your disease. See the Cancer Topics section of this Web site for a wide range of information about different types of cancer.
- Search the National Cancer Institute's (NCI) registry of cancer clinical trials. For guidance, go to Help Using the Basic Clinical Trial Search Form.
- Contact one of NCI's cancer information specialists. They can answer many of your questions about cancer and clinical trials, and guide you to further information.
- Talk about this information and how you feel about it with your health care team, family members, and friends to determine what is right for you.
What are the potential risks and benefits of clinical trials?
Potential benefits include
- health care provided by leading physicians in the field of cancer research
- access to new drugs and interventions before they are widely available
- close monitoring of your health care and any side effects
- a more active role in your own health care
- if the approach being studied is found to be helpful, you may be among the first to benefit
- an opportunity to make a valuable contribution to cancer research
Potential risks include
- new drugs and procedures may have side effects or risks unknown to the doctors
- new drugs and procedures may be ineffective, or less effective, than current approaches
- even if a new approach has benefits, it may not work for you
How are participants protected?
The government has a system designed to protect human research subjects. Before a government-funded clinical trial can begin, the trial plan (also called a protocol) must be approved. During the trial, review committees make sure that the plan is being followed and participants are being protected. See Protecting Participants in Clinical Trials for more information.
Regulations require the researchers performing studies to thoroughly inform patients about a study's treatments and tests and their possible benefits and risks before a patient decides whether or not to participate in any study. This process is called informed consent.
What is informed consent?
Informed consent is a process in which you learn the key facts about a clinical trial before you decide whether or not to participate. In addition to talking about these facts with the research doctor or nurse, they will be included in a written consent form that you can take home to read and discuss. The consent form will include details about
- the study approach
- the intervention given in the trial
- the possible risks and benefits
- the tests you may have
Don't hesitate to ask questions until you have all the information you need (see Participating in a Trial: Questions to Ask Your Doctor). While informed consent begins before you agree to participate in a trial, you should feel free to ask the health-care team any questions you have at any point. Informed consent continues as long as you are in the study. You can change your mind and leave the study whenever you want -- before the study starts or at any time during the study or follow-up period.
Could I receive a placebo?
A placebo is an inactive substance or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested in a clinical trial. In treatment trials involving people who have cancer, placebos are very rarely used.
Many treatment trials are designed to compare a new treatment with a standard treatment, which is the best treatment currently known for a cancer based on results of past research. In these studies, patients are randomly assigned to one group or another. When no standard treatment exists for a cancer, a study may compare a new treatment with a placebo. However, you will be told about this possibility during informed consent, before you decide whether or not to take part in the study.
What happens during a trial?
If you decide to participate in a clinical trial, you will work with a research team. Team members may include doctors, nurses, social workers, dieticians, and other health care professionals. They will provide your care, monitor your health carefully, and give you specific instructions about the study.
Participating in a trial may mean that you might have more tests and doctor visits than you would if you weren't in the study. Team members also may continue to stay in contact with you after the trial ends. To make the trial results as reliable as possible, it is important for participants to follow the research team's instructions. That means having all doctor visits and tests, taking medicines on time, and completing logs or answering questionnaires.
How do I take part in a Clinical Trial?
Once you've decided that participating in a clinical trial could prove beneficial to you, there are other factors to consider that might affect your participation.
Who is eligible to participate in a clinical trial?
Each study has its own guidelines for who can participate, called eligibility criteria. To ensure the strongest results, researchers want study participants to be alike in key ways. Examples of eligibility criteria for a treatment trial might be a particular type and stage of cancer, age, gender, or previous treatments. The eligibility criteria are included in the study plan. To find out if you are eligible for a particular study, talk to your doctor or the doctor or nurse in charge of enrolling patients for the study.
Where are trials conducted?
If you were to participate in a clinical trial, you might do so at a large cancer center, a university hospital, or your local medical center or physician's office.
The trial may include participants at one or two highly specialized centers or it may involve hundreds of locations at the same time. You would participate in the trial under the guidance of a team including your physician and other health professionals, who would report your experience during the trial back to the center responsible for the trial's overall coordination. Experts then use the information from all of the participants to evaluate the intervention that the trial is testing.
Who pays for the costs on a clinical trial?
The trial sponsor usually pays for the cost of the intervention being studied (for example, any drugs being compared). The sponsor also usually pays for the cost associated with any special testing or extra doctor visits that are required.
"Routine patient care costs" are the usual costs of medical care, such as doctor visits, hospital stays, clinical laboratory tests, x-rays, etc., that you would receive whether or not you were participating in a clinical trial. Some health plans don't cover these costs once you join a trial, even though studies have shown that they are not appreciably higher than costs for patients who are not enrolled in trials. (See Cost of Clinical Trials.)
Because a lack of coverage for these costs can keep people from enrolling in trials, the National Cancer Institute is working with major health plans and managed care groups to find solutions. In the meantime, there are strategies that may help you deal with cost and coverage barriers. For more information, see:Clinical Trials and Insurance Coverage - A Resource Guide
How is a Clinical Trial Planned and Carried Out?
In order to make a decision about whether to participate in a clinical trial, it helps to understand more about how trials are conceived and run. You will also want to know what happens when a trial is over.
Where do the ideas for trials come from?
The ideas for clinical trials often originate in the laboratory. Researchers develop a clinical trial protocol (the plan for a trial) after laboratory studies indicate the promise of a new drug or procedure. The first trials of a particular drug or procedure are focused on safety (phase I), and later trials focus on whether the drug or procedure is effective (phase II or phase III).
What is a protocol?
Every trial has a person in charge, usually a doctor, who is called the protocol chair or principal investigator. Phase I and phase II studies generally refer to the person in charge as the principal investigator. Phase III studies generally have a protocol chair, under whose direction multiple principal investigators carry out the protocol in participating sites. The protocol chair or principal investigator prepares a plan for the study, called a protocol. The protocol explains what the study will do, how it will be carried out, and why each part of the study is necessary. For example, the protocol includes
- the reason for doing the study
- how many people will be in the study
- who is eligible to participate in the study
- what study drugs participants will take, if any
- what medical tests they will have, if any, and how often
- what information will be gathered
Every doctor or research center that takes part in the trial uses the same protocol. This ensures that patients are treated identically no matter where or if they are receiving treatment, and that information from all the participating centers (if there is more than one) can be combined and compared.
Who sponsors clinical trials?
Clinical trials are sponsored by organizations or individuals who are seeking better treatments for cancer or better ways to prevent or detect cancer.
Individual physicians at cancer centers and other medical institutions can sponsor clinical trials themselves.
The National Cancer Institute (NCI) sponsors a large number of clinical trials. The NCI has a number of programs designed to make clinical trials widely available in the United States. Thousands of investigators at over a thousand sites participate in various aspects of NCI's clinical trials programs. These include the following.
- Cancer Centers Program: About 60 research-oriented institutions have been designated as an NCI Comprehensive or Clinical Cancer Center for their scientific excellence. The centers are key partners in the NCI's efforts to bring the benefits of clinical research directly to you. Located throughout the country, they play an important role in cancer research, delivery of the highest quality cancer care, and outreach and education for the public and professionals.
- Clinical Trials Cooperative Group Program: This program brings together groups of researchers, cancer centers, and community physicians into a national NCI-supported network. The network consists of a number of Cooperative Groups that seek to define the key unanswered questions in cancer and then conduct high-quality clinical trials at many sites around the country to answer these questions. The Cooperative Groups enroll about 20,000 new patients in treatment trials each year. Important III trials run by the Cooperative Groups help establish the state-of-the-art for cancer therapy. Additionally, the Groups perform large cancer prevention trials.
- The Community Clinical Oncology Program (CCOP). This program makes clinical trials available in a large number of local communities in the United States by linking community physicians with researchers in cancer centers. Local hospitals throughout the country affiliate with a cancer center or a cooperative group. This enables doctors to offer people participation in clinical trials more easily, without having to travel long distances or leave their usual caregivers. Several of these programs focus on encouraging minority populations to participate in trials.
Drug companies or companies that make diagnostic equipment (like X-ray machines) sponsor trials of their products, hoping to demonstrate that their products are safe and effective. The U.S. Food and Drug Administration (FDA) will only permit companies to sell a product after it has been proven safe and effective in clinical trials. For more information, see
Understanding the Approval Process for New Cancer Treatments
What happens when a clinical trial is over?
After a phase I or phase II trial is completed, the researchers look carefully at the data collected during the trial and decide whether to
- move on to the next trial with the treatment, or
- stop testing the treatment because it is not safe or effective
When a phase III trial comes to an end, the researchers must look at the data and decide if the results have medical importance. When the analysis of a phase I, phase II, or phase III trial is complete, the researchers will inform the medical community and the public of the study results.
In most cases, the results of trials are published in scientific or medical journals. To find out if the results of a study you participated in was published,
- ask the doctor or nurse in charge of your treatment.
- find out the official name of your study and search for the study in the PubMed database of medical publications. If you have trouble locating the study or searching for it, the research librarian at a university or medical library may be able to help.
- Use the NCI Clinical Trials Search Form to search for the trial among the closed protocols listed in the NCI's registry of clinical trials. Go to "Trial Status/Phase" and click on "Show Search Options." Under "Trial Status," click the button next to "Closed." Thousands of closed protocols have reference citations for published results.
Most medical and scientific journals have in place a process of peer review, in which experts critique the report before it is published, to make sure that the analysis and conclusions are sound. Particularly important results are likely to be featured by the print or electronic media, and widely discussed at scientific meetings and by patient advocacy groups. Once an intervention is proven safe and effective in a clinical trial, it may become the new standard of practice. In this way the development of better interventions for prevention, for treatment, or for detection and diagnosis is an ongoing, continuous process that builds progressively on itself to improve the quality of cancer care and prevention available to us all.
Anyone considering a clinical trial should feel free to ask any questions or bring up any issues concerning the trial at any time. The following suggestions may give you some ideas as you think about your own questions.
- What is the purpose of the study?
- Why do researchers think the approach may be effective?
- Who will sponsor the study?
- Who has reviewed and approved the study?
- How are study results and safety of participants being checked?
- How long will the study last?
- What will my responsibilities be if I participate?
Possible Risks and Benefits
- What are my possible short-term benefits?
- What are my possible long-term benefits?
- What are my short-term risks, such as side effects?
- What are my possible long-term risks?
- What other options do people with my risk of cancer or type of cancer have?
- How do the possible risks and benefits of this trial compare with those options?
Participation and Care
- What kinds of therapies, procedures and /or tests will I have during the trial?
- Will they hurt, and if so, for how long?
- How do the tests in the study compare with those I would have outside of the trial?
- Will I be able to take my regular medications while in the clinical trial?
- Where will I have my medical care?
- Who will be in charge of my care?
- How could being in this study affect my daily life?
- Can I talk to other people in the study?
- Will I have to pay for any part of the trial such as tests or the study drug?
- If so, what will the charges likely be?
- What is my health insurance likely to cover?
- Who can help answer any questions from my insurance company or health plan?
- Will there be any travel or child care costs that I need to consider while I am in the trial?
Tips for Asking your Doctor About Trials
When you talk with your doctor or members of the research team:
- Consider taking 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 hesitate 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, so that you can review them whenever you want.
Consider bringing a tape recorder to make a taped record of what's said (even if you write down answers).