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Clinical Trials

Clinical trials


A clinical trial is a research study designed to answer specific medical questions regarding cancer care.


The clinical trial is a scientific study that follows a written guideline (protocol) or recipe for treatment. It is the only scientific mechanism designed to test the effectiveness of new and promising therapies. The clinical trial provides intensive testing of new or updated treatment regimens. Almost all standard treatments in the field of oncology (cancer) originated from clinical trials. These trials are conducted by medical, surgical and radiation oncologists (cancer specialists).

Cancer clinical trials are the key to preventing, diagnosing and treating all types of cancer. It is estimated that 60% of all cancer patients in the United States are being cured. Yet, fewer than 3% of adult cancer patients participate in clinical trials. In contrast, about 71% of children enter clinical trials. This has led to major advancements in treatment and high cure rates for many childhood cancers such as Wilms' tumor (malignant neoplasm of the kidney), osteosarcoma (tumor of the bone), and childhood leukemia (cancer of the blood).

Types of clinical trials

Clinical trials that involve new drugs or devices for humans must first be tested in animals. When a new or investigational drug has been discovered that shows anti-tumor activity in laboratory animals, it is tested on a small number of patients with different types of cancer, usually in a university setting. These are called Phase I trials and are designed to test the maximum tolerated dose (MTD) and side effects or toxicities of a new drug. This phase also helps determine how a new drug should be given (by mouth or by injection). The patients being tested are those with advanced cancer who have exhausted other treatment options. These patients may not personally benefit from participation in the trial.

If the investigational agent or drug continues to show anti-tumor activity and if the side effects are tolerable and not life-threatening, the drug is moved into a Phase II trial for further testing. In a Phase II trial, the drug is offered to a specific group of patients having the same tumor type. The drug is being tested to determine if it regresses tumor growth. Additional information on side effects of the treatment is also evaluated in this phase.

If the drug continues to show response to the patient's cancer, it is moved into a Phase III trial. At this phase, the investigational treatment is compared to the standard cancer therapy. This is to ensure that no one in a study is left without any treatment when standard treatment is available. If there is no standard therapy, a placebo (a pill that looks like the drug being studied but contains no active medication) may be used for comparison. However, researchers must inform potential patients of this possibility before patients decide whether to participate. Patients are usually assigned their treatment by a process called randomization, which is similar to the toss of a coin. Comparison or randomized trials help researchers find the most effective treatment for a specific type of cancer.

The objectives of Phase III trials include tumor response to treatment, survival, and quality of life during therapy. This phase can involve 400-1000 patients. Anti-tumor response by a significant proportion of the involved patients indicates that the investigational drug or treatment is ready to be submitted to the Food and Drug Administration (FDA) for approval. If approved, the drug is released from investigational status and made available for commercial use in patients with the specifically tested type of cancer.

What to expect as part of a clinical trial

Taking part in a clinical trial does not mean that patients are seen as or treated like "guinea pigs, " or that they will receive substandard care. Cancer patients who enroll in clinical trials may be the first to receive a new technique or drug that becomes the standard of care. Clinical trials, however, have risks, as well. The treatment or drug being tested is new, and the side effects may be unknown. The cancer patient, his or her loved ones, and the patient's physician must weigh the risks and benefits when deciding whether or not to enroll in a clinical trial.

When patients participate in a clinical trial, they receive treatment in a cancer center, hospital, clinic, and/or doctor's office. Doctors, nurses, social workers, and other health professionals may be part of the treatment team, and will closely monitor progress. Cancer clinical trial patients:

  • are, as stated above, under close scrutiny
  • are seen frequently by the members of the treatment team
  • are tested often
  • follow the treatment plan their doctor prescribes and as according to the study's protocol
  • and may also have other responsibilities, such as keeping a log or filling out health forms.

Some studies continue to check on patients after their treatment is completed.



Klimaszewski, Angela D., Jennifer L. Aikin, Monica A. Bacon, Susan A. DiStasio, Heidi E. Ehrenberger, Bertie A. Ford, Ed. Manual for Clinical Trials Nursing. Pittsburgh: Oncology Nursing Press, Inc., 2000.

Murphy, Gerald P., Walter Lawrence, Jr., and Raymond E.Lenhard, Jr., Ed. American Cancer Society Textbook of Clinical Oncology. Atlanta: American Cancer Society, 1995.

Varricchio, Claudette, Ed. A Cancer Source Book for Nurses. Atlanta: Jones and Barlett Publishers, 1997: pp. 69-79.


National Cancer Institute. An Introduction to Clinical Trials. January 2000 National Cancer Institute. 8 July 2001. <>.

National Cancer Institute. Cancer Trials. 8 July 2001. <>

Phyllis M. Stein, B.S., CCRP



Cancer of the blood and bone marrow.

Maximum tolerated dose (MTD)

The highest dose of an investigational drug that patients can tolerate without life-threatening or fatal side effects.


The study of cancer.


A tumor of the bone. The most common childhood cancer.


A preparation without medication.


A written, scientific guideline used for treatment planning in clinical trials.

Wilms' tumor

A malignant tumor of the kidney; occurs most frequently in children.


  • Am I eligible for a clinical trial?
  • Where can I get more information?

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"Clinical Trials." Gale Encyclopedia of Cancer. . 14 Dec. 2017 <>.

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Clinical Trials

Clinical trials


A clinical trial is a carefully designed research study that is carried out with human volunteers. The trial is designed to answer specific questions concerning the effectiveness of a drug, treatment, or diagnostic method, or to improve patients' quality of life.


Qualification for a clinical trial involves the selection of various desirable criteria (inclusion criteria), as well as criteria by which volunteers are rejected (exclusion criteria). Typical criteria include age, gender, the type and severity of the disease, prior treatment, and other medical conditions.

Depending on the clinical trial, the volunteers that are recruited could be healthy or ill with the disease under study. There are a number of different types of clinical trials that utilize differing types of study plans (protocols). A treatment trial evaluates a new treatment, new drug combinations, new surgical strategies, or innovative radiation therapy. A prevention trial seeks to find better ways to prevent disease from occurring or prevent disease from returning. Medicines, vaccines, vitamins, and lifestyle changes can all be candidates for a prevention trial. A diagnostic trial is designed to find better means of diagnosis for a particular disease or medical condition. A screening trial is designed to determine the best way to detect a particular disease or medical condition. Finally, a quality of life trial (supportive care trial) seeks to improve the comfort and daily life of people with a chronic illness.

Clinical trials, particularly treatment and prevention trials, often have several components, or phases. The following phases (I-IV) relate to the scope of the trial:

  • Phase I trial evaluates the new drug or treatment in a small group of people (less than 100). Humans do not necessarily need to participate in such a trial. Experiments in the lab using microbiological cultures or tissue cells may suffice. The trial's purpose is to provide early indications of a drug or treatment's safety, safe dosage range, and reveal any side effects.
  • Phase II trial follows a phase I trial. A promising drug or treatment is tested on a larger group of people (100300) to better determine the effectiveness and to monitor safety more critically. Use of a larger population can help reveal side effects that could be hidden by the use of only a few volunteers.
  • Phase III trial evaluates a drug or treatment that has proven effective in the phase I and II trials and is tested on a large population (1,0003,000) to confirm its effectiveness, reveal any rarer side effects, and gather information that will allow the drug or treatment to be safely marketed.
  • Phase IV trial occurs after a product has been released in the marketplace. Monitoring of a drug or treatment in very large numbers of people provides further information on benefits and risks.

A typical clinical trial involves medical doctors and nurses, although social workers and other health care workers may also contribute. The members of the clinical team monitor the health of each volunteer at the outset and during the trial, give instructions, and often provide follow-up after the trial is completed. For a clinical trial volunteer, this means more visits to the health care facility than would normally occur, although compensation such as transportation expense is sometimes provided.

A critical part of a clinical trial is obtaining the consent of volunteers for their participation. It is mandatory that a trial's risks (i.e., side effects, little or no effect of treatment) and benefits (i.e., more proactive role in health care, access to new therapies, advance medical care) be clearly explained to participants. Once this is done, volunteers provide their informed consent by signing a document. This document is not legally binding, so volunteers are not obligated to complete the trial. An ethical clinical trial will never reveal the identities of the volunteers.

In addition to the drug being studied, clinical trials of new drugs will typically use a pill, liquid, or powder that looks the same as the active compound, but that has no medicinal value. This inactive compound, known as a placebo, is usually given to the control group of volunteers, who are compared to the test group that receives the active drug. Usually the volunteers do not know whether they receive a placebo or the active drug. A clinical trial can be designed so that the researchers are also unaware of which people receive the active drug. When volunteers and researchers are both unaware, the trial is described as being double blind. Volunteers are often assigned to the control or test groups at random. This action is designed to minimize any bias due to age, gender, race, or other factors.



"An Introduction to Clinical Trials." January 21, 2004 (March 30, 2004). <>.


National Institutes of Health, Clinical Center. 6100 Executive Blvd., Suite 3C01MSC 7511, Bethesda, MD 20892-7511. (301) 496-2563 or (800) 411-1222; Fax: (301) 402-2984. <>.

Brian Douglas Hoyle, PhD

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Clinical Trials

Clinical Trials

A clinical trial is a prospective study of the effectiveness of a new treatment, such as a drug, surgical technique, or medical device. The term prospective indicates that there is a well-defined starting point from which the subjects are tracked for some definite period of time. Before a clinical trial is conducted, laboratory experimentation and animal trials on the proposed treatment is performed.

Clinical trials must meet strict government guidelines established by the U. S. Food and Drug Administration (FDA) to assure the safety of subjects and the scientific validity of the trial. Prior to admission to a clinical trial, subjects must meet the study requirements and be sufficiently informed regarding the purpose of the trial. A new treatment may have major benefits but may also have significant side effects for the type of patient that it could help. Careful screening and examination help select persons who meet the trial's design and intent. Informed consent, required of all participants, will alert the subjects not only to the purpose and design of trial with its potential benefits but to any known or suspected side effects or complications.

A phase I trial is a small-scale test in healthy volunteers to determine the general safety of the treatment with human subjects. Phase II tests the safety and effectiveness of the new treatment in a small group of patients who might benefit. A phase III trial is a large-scale study to scientifically document the value of the proposed drug, technique, or device. Phase IV studies allow the long-term follow-up of patients to determine side effects and continued effectiveness after a treatment reaches the market.

The expense involved in clinical trials is due to the extensive development and research costs, initial laboratory testing, and their large-scale nature. Conducted at multiple sites around the country, clinical trials have significant infrastructure for record-keeping, follow-up, dissemination, and safety.

Craig Clifford


Friedman, L. M., C. D. Furberg, and D. L. DeMets. Fundamentals of Clinical Trials, 3rd ed. New York: Springer-Verlag, 1998.

Whitehead, John. The Design and Analysis of Sequential Clinical Trials, 2nd ed. New York: John Wiley & Sons, 1997.

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Clinical Trials Network


In an effort to find the most effective treatments for drug addiction, the National Institute on Drug Abuse (NIDA) has established a clinical trials research network to test new pharmacological and behavioral treatments in diverse patient populations. Clinical trials have been used for diseases such as cancer and AIDS as a fast, effective, and safe way to test new treatments. Also, as with other diseases, there are a number of effective treatments for addiction. However, the efficacy of these new treatments has been demonstrated primarily in specialized treatment research settings, with somewhat restricted patient populations. As a consequence, few of these new drug-abuse treatments are being applied on a wide-scale basis in real-life practice settings

In response, NIDA has established the National Drug Abuse Treatment Clinical Trials Network (CTN). The CTN is based on a model used successfully by other NIH institutes, including the National Cancer Institute, the National Heart Lung and Blood Institute, and the National Institute of Allergy and Infectious Diseases. The CTN provides a research infrastructure to test whether new and improved treatment components are effective in real-life settings with diverse patient populations.


NIDA has established the first six nodes of the CTN in various regions of the country. Each node or functional unit of the CTN is affiliated with a research-based organization and a number of drug-abuse treatment programs in the community. The CTN brings together researchers and practitioners as partners to conduct full-scale testing of promising new medications and behavioral treatments in a wide range of community drug-abuse treatment settings with patients from a variety of ethnic and social back-grounds. (The nodes to date include nodes in New England, the Delaware Valley, the Mid-Atlantic, the Northwest, the Pacific region, and New York.) Each of these centers is linked with at least five community treatment programs in its region. CTN research is carried out in the community-based treatment setting. Each node works with the other nodes and with NIDA to conduct multisite and cross-regional clinical trials research.


The overall goal of the CTN is to improve the quality of drug-abuse and addiction treatment throughout the nation using science as the vehicle. Toward this end, the mission of the CTN is threefold:

  1. Conduct studies of behavioral, pharmacological, and integrated behavioral and pharmacological treatment interventions in multisite clinical trials to determine effectiveness across a broad range of community-based treatment settings and diversified patient populations.
  2. Transfer the research results to physicians, providers, and their patients to improve the quality of drug abuse treatment throughout the country using science as the vehicle.
  3. Provide advice on changing policies to ensure the delivery of effective therapies in community-based treatment programs.


Three science-based treatment research protocols will start in 2000, including two behavioral therapies developed to enhance treatment outcomes, and one that will test a new medication for use in opiate detoxification. Several other protocols are currently being developed. All treatment components to be tested have been shown to be effective in controlled research environments.

When complete, it is expected that the network will consist of twenty to thirty nodes consisting of regional research treatment centers linked to ten to fifteen community-based treatment programs that represent the variety of settings and patient populations prevalent in that particular region of the country. The CTN will help ensure that treatment research in drug abuse and addiction meets the needs of the wider community, including minorities, women, children, adolescents, and underserved populations. The CTN will also be useful to other aspects of NIDA's research portfolio. For example, multi-site clinical trials with diverse patient populations will provide a valuable resource to researchers interested in elucidating genetic and environmental determinants of vulnerability. Ultimately, increased understanding of the roles played by genetics, environment, and their interaction in shaping an individual's susceptibility to drug addiction will lead to a variety of more targeted drug abuse prevention and treatment approaches. For more information, visit NIDA's website at

For more information about NIDA's National Drug Abuse Treatment Clinical Trials Network, visit the NIDA website at

Alan I. Leshner

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