Understanding Clinical Trials
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Interpreting clinical trial results
A clinical trial is also known as a study. You may have questions about how studies are organized and what the study results mean for a certain treatment.
One of the most reliable ways to show if a treatment works is to test it in a randomized controlled clinical trial. Here you’ll find information about why this study method is so reliable, as well as other helpful information about clinical studies.
What is a randomized controlled clinical trial?
In a randomized controlled clinical trial, the participants are divided by chance (randomized) into different groups (treatment arms). Each group receives a different treatment. The results from each group are then compared. The trial may test 2 or more therapies at the same time, so it's possible to compare their effectiveness and safety. A nonrandomized controlled trial gives all patients the same therapy, so the results cannot be compared with another therapy.
Randomized controlled trial
Nonrandomized controlled trial
Why is it important to compare treatments?
A randomized controlled trial that compares treatment results is the preferred way to do a clinical trial because it aims to reduce the chance of bias for or against a treatment. This type of study means that every child has the same chance of being in a treatment arm and it helps the researchers compare the results fairly.
Does it matter which patients are included in a study?
Each study has guidelines about which patients can be in the study. Patients in a study can be different ages. They may have different weights and heights. They may be male or female or both. However, all the patients should have the same type or stage of disease and they should all have had the same or similar treatments before the study starts. This helps the researchers compare the results of the treatments in the study more effectively.
Does it matter how many patients are included in a study?
Generally, the more people enrolled in a study, the more reliable the results will be. The number of patients enrolled in a study is known as the sample size. A large sample size lets researchers more clearly see a difference between the treatment results.
Where do study patients come from?
Clinical studies can enroll patients from multiple institutions, such as hospitals, cancer care centers, or cancer clinics, or from a single institution. Multiple-institution studies are preferred because they help show if the results are the same across more patients in many different places in the United States and/or around the world.
How was the study treatment evaluated?
Randomized controlled trials may use different outcome measures to evaluate how well a new treatment works. Event-free survival (EFS), overall survival (OS), and objective response (OR) are all different ways that studies can measure how well a therapy is working. It is important to avoid comparing studies that use different outcome measures. You can read more about each below.