Most cancer trials are treatment or interventional trials that involve people who have cancer. They are designed to answer specific questions about the effectiveness of a treatment, if it is safe, if the treatment prolongs life with fewer side effects and better quality of life, and if it prevents the cancer from coming back. These trials test many types of cancer treatments, including new drugs, vaccines, approaches to surgery or radiation therapy and combinations of treatments.

These trials look at ways to improve quality of life in cancer patients, particularly those experiencing side effects from treatment. Some options might include medications to address physical side effects, nutritional interventions, and psychosocial options such as support groups or one-on-one support. These trials are aimed at patients or their caregivers needing help coping with cancer.

These trials usually involve healthy individuals, high-risk individuals, and those who have had cancer and have a high risk of developing a new cancer. Prevention trials look at cancer risk and ways to reduce the risk either by drugs to reduce the risk or behavior modifications such as diet and exercise. People in these studies are often followed for several years to determine the long-term effects on prevention.

The goal of these trials is to find cancer early when it may be more treatable. A successful trial will reduce the number of deaths from the cancer being screened for.