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.
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.
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.
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.