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Types of Clinical Trials

There are several types of cancer clinical trials, including treatment trials, prevention trials, screening trials, supportive and palliative care trials. Each type of trial is designed to answer different research questions.

Treatment trials

Most cancer clinical trials are treatment studies that involve people who have cancer. These trials test new treatments or new ways of using existing treatments, such as new drugs, vaccines, approaches to surgery or radiation therapy, or combinations of treatments.

Some treatment trials involve testing cancer cells for the presence of specific molecular markers. These markers can include changes in certain genes or proteins. These changes may help to further classify cancers and certain treatments may target them. So it is important to know whether they are present.

Treatment trials are designed to answers questions such as:

  • What new treatment methods can help people who have cancer?
  • What is the most effective treatment for people who have cancer?
  • Does the new treatment work as well as the old treatment?
  • What are the new treatment’s side effects?

For information about taking part in treatment trials, see the booklet Taking Part in Cancer Treatment Research Studies.

Prevention trials

Cancer prevention trials are studies involving healthy people. In most prevention trials, the participants either do not have cancer but are at high risk for developing the disease or have had cancer and are at high risk for developing a new cancer. These studies look at cancer risk and ways to reduce that risk.

There are two kinds of prevention trials, action studies and agent studies.

Action studies ("Doing something") focus on finding out whether actions people take—such as exercising more or eating more fruits and vegetables—can prevent cancer.

Agent studies ("Taking something") focus on finding out whether taking certain medicines, vitamins, minerals, or dietary supplements (or a combination of them) may lower the risk of a certain type of cancer. Agent studies are also called chemoprevention studies.

Researchers who conduct these studies want to know:

  • How safe it is for a person to take this agent or do this activity?
  • Does the new approach prevent cancer?

For information about taking part in prevention trials, see the booklet If You Want to Find Ways to Prevent Cancer…Learn About Prevention Clinical Trials.

Screening trials

The goal of cancer screening trials is to test new ways to find disease early, when it may be more easily treated. An effective screening test will reduce the number of deaths from the cancer being screened.

Researchers who conduct cancer screening studies want to know:

  • Does finding disease earlier, before people have any symptoms, save lives?
  • Is one screening test better than another?
  • Do a large number of people who receive the screening test undergo unnecessary follow-up tests and procedures?

Quality-of-life/supportive care/palliative care trials

These trials look at ways to improve the quality of life of cancer patients, especially those who have side effects from cancer and its treatment. They find new ways to help people cope with pain, nutrition problems, infection, nausea and vomiting, sleep disorders, depression, and other health problems.

Trials might test drugs, such as those that help with depression or nausea. Or, they might test activities, such as attending support groups, exercising, or talking with a counselor. Some trials test ways to help families and caregivers cope with their own needs, as well as those of the person with cancer.

Researchers who conduct these studies want to know:

  • How does cancer and its treatment affect patients and their loved ones?
  • What can improve the comfort and quality of life of people who have cancer?
  • Updated: November 2, 2012