What is a Clinical Trial?


Clinical trials are used to determine the most effective and safest treatment for a disease. Each trial is aimed at improving survival rates or reducing side effects or late effects of treatment. People often hear about clinical trials and think that a patient in a trial may or may not receive medicine. Those who do not receive medicine in a trial are said to be receiving placebos. In nearly every clinical trial, patients receive medication. This means patients are not receiving placebos.

It is also important to understand that clinical trials are standard practice in cancer treatment for children, adolescents and young adults. While less than five percent of adults with cancer are enrolled in clinical trials, 60 percent of patients under age 29 diagnosed with cancer are enrolled in trials. Participation in clinical trials spans an average of two to three years and requires a lifetime of follow-up care.

Development and Review of Clinical Trials

Many people and organizations are involved in developing a clinical trial. For each new clinical trial, a group of doctors, nurses and other experts propose how the treatment should be given. Many experts review the trial before it is sent to the National Cancer Institute (NCI) for approval. The institutional review board (IRB) of each hospital participating in a clinical trial must also approve the trial, in part to make sure that the rights of patients who will be enrolled in the trials are protected. It is helpful to understand that each trial is reviewed many times by different experts before being started at a treatment center.

Types of Clinical Trials

There are two types of clinical research trials, therapeutic and non-therapeutic.

  • Therapeutic trials are ones which enroll patients and provide a specific treatment to the patients to study its impact on cancer.
  • Non-therapeutic trials are ones which do not provide a treatment to patients, but instead study important factors which help advance the understanding of cancer and its impact. For example, some non-therapeutic studies collect tissue specimens to examine the cellular structure of a cancer tumor. Other studies track epidemiological information such as the long-term health effects of chemotherapy. Non-therapeutic studies often lead to therapeutic ones.

Within therapeutic trials, there are three different phases used to evaluate new treatments. Each phase has a different goal.

  • Phase I studies are the most basic of clinical trials. Here, drugs are tested to evaluate the dosages of the treatment, and how often the treatment can be administered (maximum tolerated dosages, MTD). As it is unknown whether the treatment will be effective against a particular disease, people with a variety of diseases are enrolled. Drugs are given at gradually increasing dosages until there are unacceptable side effects (dose-limited toxicities, DLT).
  • Phase II studies use the results from Phase I studies regarding MTD and DLT. The treatment is targeted at the population of patients which responded most favorably in Phase I trials, because it is believed to hold promise for that particular group of patients.
  • Phase III studies are those that most children will receive when newly diagnosed. These studies will test the standard treatment (current best) against promising alternatives that may increase cure rates or decrease side effects or late effects of treatment.

Your child may be in a Phase III clinical trial that compares two or more treatments (called study “arms”). Each treatment has been shown to be effective in other studies but not yet compared to each other or the current best treatment. Usually, one treatment arm is the "standard" or the best proven current treatment. The other (new) treatment has some changes or additions to determine if they cure the disease in more children, control disease longer, cause fewer or less serious side effects, or change the number of days spent in the hospital. If a clinical trial is not currently available at the time your child is diagnosed, your child will receive the best standard treatment.

To learn if one treatment in a Phase III clinical trial is better, each child is assigned randomly to one of the treatments. Assigning children randomly is a process like flipping a coin that assures that each child has a fair and equal chance of being assigned to either/any of the treatments. In most studies, we do not know which treatment is better until all the children taking part in the clinical trial have completed treatment and have been observed for several years. However, if one of the treatments is already found to be better than the others while the trial is still going on, the trial is stopped, and all children are given the better treatment. If for any reason the treatment plan is found to be not the best for your child, the plan will be changed.

Individual Drug Studies

Individual drug studies can be conducted at a large or small number of hospitals, depending on the purpose of the trial. In individual drug studies, a drug manufacturer closely monitors lab tests and results from the use of the drug, and releases only a small amount of the drug during the period of the study. These studies are usually performed at centers that are well equipped to gather the needed data and to provide a quick transfer of lab specimens.

Supportive Care Studies

Supportive care studies evaluate ways of helping with the side effects of treatments. These can also be performed at a few medical centers at a time or at many hospitals at once. Most often though, these research questions can be answered with fewer patients. Once the results are shared, patient outcomes may be improved sooner than through a large national study.

Limited Institution Trials

Sometimes, clinical trials are performed in only a few hospitals. These are called Limited Institution Trials and they are able to answer a research question with fewer patients than most national trials require. Answers to important research questions can be obtained in a shorter time through such limited trials. COG limited institution trials are reviewed and approved in the same manner as all other clinical trials.

Pilot studies

Pilot studies are examples of limited institution trials. In these studies, investigators are studying a new treatment or therapy combination. Such studies are done at only a few institutions with a limited number of patients to see if the treatments are safe and effective against the targeted disease. If it is found to be effective, the new therapy may be open to more institutions. The results of pilot studies are compared to the best current treatments to find out if the new treatments are better in some way. Pilot studies also help to decide whether the drugs or therapies being tested should be investigated further using more patients.

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