Researchers all over the world are looking for new and better ways to prevent, detect, diagnose, and treat cancer. They are learning more about what causes cancer. They are conducting many types of clinical trials.

A clinical trial is one of the final stages of a long and careful research process. The search for new treatments begins in the lab. If an approach seems promising in the lab, the next step is to see how the treatment affects cancer in animals and whether it has harmful effects. Of course, treatments that work well in the lab or in animals do not always work well in people. Clinical trials are needed to find out whether new approaches to cancer prevention, detection, diagnosis, and treatment are safe and effective.

Clinical trials contribute to knowledge and progress against cancer. Research already has led to many advances, and scientists continue to search for more effective approaches. Because of progress made through clinical trials, many people treated for cancer are living longer. Many of these cancer survivors also have a better quality of life compared to survivors in the past.

There are several types of clinical trials:

• Prevention trials: These studies look at whether certain substances (such as vitamins or drugs), diet changes, or lifestyle changes can lower the risk of cancer.
• Screening trials: These studies test methods of finding cancer before a person has any symptoms. Researchers study lab tests and imaging procedures that may detect specific types of cancer. For example, researchers are learning the risks and benefits of virtual colonoscopy (CT scan of the colon) for colon cancer screening. Other scientists are comparing spiral CT scan and chest x- rays for lung cancer screening.
• Treatment trials: Treatment studies look at new treatments and new combinations of existing treatments. Examples include the study of drugs that kill cancer cells in new ways, new methods of surgery or radiation therapy, and new approaches such as vaccines.
• Quality of life (supportive care) trials: Scientists study ways to improve the comfort and quality of life of people with cancer. For example, doctors may study drugs that reduce the side effects of chemotherapy. Or they may explore ways to prevent weight loss or control pain.

People who join clinical trials may be among the first to benefit if a new approach turns out to be effective. And even if participants do not benefit directly, they still make an important contribution by helping doctors learn more about cancer and how to prevent, detect, and control it. Although clinical trials may pose some risks, researchers do all they can to protect their patients.

People who are interested in being part of a clinical trial should talk with their doctor. They may want to read the NCI booklet Taking Part in Cancer Treatment Research Studies. It explains how clinical trials are carried out and explains their possible benefits and risks.