Clinical trials are research studies involving people. Clinical trials are designed to evaluate whether a new development is safe, effective, and better than the current standard of care. These interventions can include new drugs, new combinations of existing therapies, new approaches to radiation therapy or surgery, new methods of treatment, complementary or alternative therapies, and new prevention methods. Cancer clinical trials are designed to compare an investigational therapy with the standard treatment regimen being used at the time. Placebo-controlled clinical trials in cancer research are rare, but are used when there is no effective, standard treatment available.

Other types of cancer clinical trials study new ways of preventing, screening, or diagnosing cancer or improving a person's quality of life. In clinical trials, the different treatment groups are sometimes called arms.

Cancer clinical trials have led to scientific advances that have increased doctors' understanding of how and why tumors develop and grow. The knowledge gained has helped scientists and doctors develop new ideas on how to slow, halt, and even prevent the development of the disease. Because clinical trials can involve hundreds or even thousands of individual patients, it can take a long time to find out the results. Still, clinical trials remain the most reliable route to definitive answers and are the only accepted scientific method to determine if a new treatment works better than the current standard of care.

Clinical trial guidelines/how clinical trials are set up

All clinical trials have guidelines about who can participate, called inclusion and exclusion criteria. These guidelines are based on a person's age, type of disease, medical history, and current medical condition.

Inclusion criteria help ensure that all the people in the clinical trial are medically similar. For example, the inclusion criteria may require that each participant have the same kind of cancer or same stage of disease (such as stage IIA colorectal cancer). If the people have too many medical differences, the doctors will have more difficulty interpreting the results.

Likewise, exclusion criteria help keep people safe. They are not used to reject people personally. For example, it is often not safe for women who are pregnant, or who may become pregnant, to receive certain cancer treatments, so they may be excluded from clinical trials.

Each clinical trial follows a set of rules called a protocol. A protocol describes inclusion and exclusion criteria; the schedule of tests, procedures, medications, and doses; and the length of the study. While in a clinical trial, participants are seen regularly by the research staff to monitor their health and determine the safety and effectiveness of the treatment.

Clinical trial participants work with a research team. The research team includes doctors, nurses, social workers, and other health-care professionals. They will check the persons health at the beginning of the trial, give specific instructions for participating in the trial, monitor the person carefully during the trial, and stay in touch with the person after the study. A person's participation will be most successful if they follow the protocol carefully and stay in contact with the research staff..

Sponsorship and coverage

Clinical trials are sponsored by government agencies such as the National Institutes of Health (NIH), the National Cancer Institute (NCI), pharmaceutical companies, individual doctors, health-care institutions such as health maintenance organizations (HMOs), and organizations that develop medical devices or equipment. Trials can take place in hospitals, universities, doctor's offices, or community clinics.

One effective mechanism for operating clinical trials is a cooperative group. Cooperative groups are large networks of doctors and other health-care professionals from many different institutions that develop and coordinate clinical trials. Cooperative groups are funded by the NCI. Because so many doctors and institutions are involved, the trials sponsored by cooperative groups can enroll more people than a single trial at one hospital. Also, the cooperation makes it easier for people from different parts of the country to enroll in a clinical trial. Find a cancer center or cooperative group.

The coverage of clinical trial costs differs by state. Medicare covers routine costs related to phase II or phase III trials. Some clinical trials offer payment, while others do not. In some programs, researchers will reimburse for expenses associated with participating in the research such as transportation, childcare, meals, and accommodations.

Despite the promise offered by clinical trials, less than 5% of adult cancer patients enroll in them. This lack of participation slows progress in the development of new, more effective therapies. By contrast, more than 60% of children with cancer are enrolled in clinical trials. Approximately three-quarters of children with cancer survive their disease long-term, compared with half of adults. The increased survival rate for children can be directly linked to their higher rate of participation in cancer clinical trials.

Additional resources

About Clinical Trials section of CancerTrialsHelp.org, the website of the Coalition of National Cancer Cooperative Groups. This section is designed to help people learn more about cancer clinical trials.

Cancer Research: A Guide to Clinical Trials is an adaptation of CancerTrialsHelp.org's patient advocate cancer clinical trials education program in the form of an interactive guide that gives the public access to extensive information about a variety of topics ranging from the basics about clinical trials to drug development to patient safety.

More Information

Feature: Clinical Trials: Medicine's Method for Answering Questions

ASCO Fact Sheet: Clinical Trials: The Key to Progress in Cancer Research (PDF)