Men and women of all ages and backgrounds take part in these studies. Usually:

• They are healthy people.
• They are people who want to lower their chances for getting a certain cancer.

Each study has different rules about who can join. For example:

• One study may have people of a certain age or sex.
• One study may have people with a certain family history.

There are prevention studies for men and women of all ages and backgrounds. You may know someone--a friend, relative, neighbor, or co-worker--in a study now.