Cancer: Taking Part in Clinical Trials

by National Cancer Institute

Types of Prevention Trials

This information may interest you if you have a higher risk for a certain type of cancer than most people, or you may want to learn about ways to prevent cancer. There are two types of prevention clinical trials that study ways to reduce the risk of getting cancer:

Action studies (doing something) These focus on finding out whether actions people take, such as getting more exercise or quitting smoking, can prevent cancer.

Agent studies (taking something) These studies (also called chemoprevention studies) focus on learning whether taking certain medicines, vitamins, minerals, or food supplements can prevent cancer.

This information focuses on agent studies designed to prevent cancer. When "cancer prevention trials or studies" are mentioned in this resource, they refer only to agent studies.

What Is Cancer?

Cancer occurs when, for unknown reasons, cells divide without control or order. All parts of the body are made up of cells that normally divide to produce more cells only when the body needs them. When cancer occurs, cells keep dividing even microscopewhen new cells are not needed. The change from normal to cancerous cells requires several separate, different gene alterations. Eventually uncontrolled growth from altered genes may produce a tumor that can be benign (not cancer) or malignant (cancer). Malignant tumors can invade, damage, and destroy nearby tissues and spread to other parts of the body. A benign tumor won't spread to other parts of the body, but local tissue may be damaged and the growth may need to be removed.

What Are Cancer Risk Factors?

A cancer risk factor may mean you have an increased chance to develop cancer. It doesn't mean that you will develop cancer. Some people have a greater than average chance to get a certain cancer because they have one or more risk factors.

Doctors are still learning the role of risk factors in different cancers. Some risk factors make it very likely that a person will develop cancer; others seem to increase a person's risk only slightly.

Risk factors fall into four broad groups and can overlap. For some cancers, different types of risk factors can work together to increase cancer risk.

1. Lifestyle or behavioral risk factors.

These are things people do that make it more likely that they will develop cancer. For example, smoking is strongly linked to lung cancer and a type of sunlight rays (ultraviolet, or U.V., rays) are linked to melanoma, a form of skin cancer.

Lifestyle factors can also reduce cancer risk, such as eating plenty of fruits, vegetables, and fiber to lower the risk for cancer of the colon and rectum.

2. Hereditary risk factors.

There are altered or changed genes that are passed on from parent to child, making a person more likely to get cancer. For example, changes in two genes - BRCA1 and BRCA2 - can make a person more likely to get breast cancer.

If you know that one type of cancer seems to run in your family, you may wish to speak with a trained genetic counselor. The counselor can answer many of your questions about cancer risk. You also may be able to get a test to see if you were born with a higher risk for getting cancer. Some people worry about how they'll feel if they learn they have a higher risk for cancer, especially if there's no method available to reduce their risk. Other people want to know, no matter what.

3. Environmental risk factors.

There are agents such as asbestos and radon that are linked with a higher cancer risk (an increased risk for cancer). People are sometimes exposed to cancer-causing agents in their workplace.

4. Medical risk factors.

Certain health conditions may increase a person's risk for some cancers, for example:

colon polyps - abnormal growth of tissue in the lining of the bowel.

previous cancer- having had radiation or chemotherapy treatment for illness, such as breast cancer, may put you at higher risk for the same type of cancer to return or to get a different type of cancer.

If a person has one or more of these risk factors, he or she may want to know more about cancer prevention trials. If you think you may be at risk for getting cancer, you can find out whether or not you are eligible to join a cancer prevention study.

What Is a Cancer Prevention Clinical Trial?

What Is a Clinical Trial?

Clinical trials, also known as clinical studies, are research studies in which people help doctors find ways to improve health and health care. Many of today's treatments for cancer are based on the results of past clinical trials. Examples include clinical studies to treat or prevent breast and childhood cancers. Because of progress made through clinical trials, many people treated for cancer are now living longer.

In cancer prevention trials, people take medicines, vitamins, minerals or other supplements that doctors believe may lower the risk of a certain type of cancer. Scientists who conduct these studies want to learn:

• Does the medicine or supplement (often called a study agent) prevent cancer?
• How safe is it to take the study agent?

How Are Cancer Prevention Clinical Trials Different from Other Cancer Studies?

There are different types of cancer clinical trials or studies. They include:

• chemoprevention trials designed to help people who have not previously had cancer;
• chemoprevention trials designed to prevent a new type of cancer from developing in people who have had cancer;
• early detection trials to find cancer, especially in its early stages;
• treatment trials to test new treatments in people who have cancer; and
• quality of life studies to improve comfort and quality of life for people who have cancer.

Some studies, such as treatment clinical trials and quality-of-life studies, are for people who already have cancer. Certain chemoprevention trials are for people who are cancer survivors who want to lower their risk for getting another cancer. This booklet describes cancer prevention trials or studies for people who haven't had cancer. People in these trials are usually healthy people who want to lower their risk for the disease.

About the Author

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