Because researchers want to make sure that whatever happens in a clinical trial is the result of the new treatment or procedure and not just chance, the people eligible to participate in a clinical trial are limited to a group with very specific characteristics. For example, a study comparing the effectiveness of an aromatase inhibitor with tamoxifen might be looking for participants with the following characteristics:
- postmenopausal women
- diagnosed with early-stage, hormone-receptor-positive breast cancer
- have had surgery to remove the cancer
- may or may not have had chemotherapy
- have not taken tamoxifen or any other hormonal therapy
A person has to meet ALL of the eligibility requirements to participate in the trial. Part of the process involves enrolling patients who are alike in certain ways. For example, a trial might be designed to answer questions about treating patients who have a particular stage of breast cancer, or who have already received a certain type of chemotherapy. In order for the results to make sense at the end of the study, only those patients who meet these criteria will be enrolled.
Another consideration is patient safety. A new medicine may be safe only in people with normal kidney or liver function, for example. So people with poorly functioning kidneys or livers would not be accepted into the study. However, there are still many people who are eligible to participate in clinical trials.
According to the American Cancer Society, a shortage of people taking part in clinical trials is the biggest reason trials aren't done. It's estimated that fewer than 5% of adults diagnosed with cancer will take part in a clinical trial.
Many people say they didn’t know they were eligible to be part of a clinical trial. Other people aren't willing to be study subjects or are worried that they might be harmed by a new treatment. The uncertainty of not knowing how a trial will turn out can make it hard to decide if you want to participate. In rare cases, clinical trial volunteers have been hurt by the treatment or procedure being tested. At the same time, hundreds of thousands of people have been helped and are alive because other people chose to participate in a trial resulting in the approval of a new treatment. While clinical trials are important, the choice to participate in one is very personal and depends on your unique situation. Like any breast cancer treatment, you and your doctor need to weigh the benefits against the risks and decide what's best for you.