Who can join a study?

Before any clinical trial or other research study begins, researchers develop the protocol for that study. This detailed plan describes the study’s design, the reasons for doing the study, and who can join (known as the eligibility criteria).

Eligibility criteria

Before any clinical trial or other research study begins, researchers develop the protocol for that study. This detailed plan describes the study’s design, the reasons for doing the study, and who can join (known as the eligibility criteria).

The eligibility criteria are the rules for who can take part in the research study. They outline the features that must be shared by all participants to ensure that the people taking part are similar in certain ways. This is so the results of the study will be clearly related to the treatment, not to other individual factors.

Depending on the research, the eligibility criteria may include:

• age or sex
• cancer type
• stage of the cancer
• symptoms or side effects experienced
• length of time since diagnosis or treatment
• previous treatments for the cancer
• other medical conditions.

Eligibility criteria can be broken down into:

• inclusion criteria – the features a person needs to have to join a research study
• exclusion criteria – the features that stop someone from taking part.

The eligibility criteria also help keep people safe by considering things that might make the trial too risky for them. For example, you may be excluded from a trial if you are pregnant, have high blood pressure, or have some other condition that increases the risks of the treatment.