What Is a Clinical Trial and How Do They Work?

Clinical trials are the engine of evidence-based medicine — the rigorous scientific process by which new treatments, interventions, diagnostic tests, and preventive strategies are tested in human beings before they enter widespread clinical use. Without clinical trials, medicine would still be driven by anecdote, tradition, and individual physician experience. With them, we can know with genuine confidence whether a new cancer drug extends survival, whether a vaccine prevents disease, or whether a new surgical technique is better than the standard one.

What Is A Clinical Trial?

A clinical trial is a research study conducted in humans to evaluate medical, surgical, or behavioral interventions. Clinical trials can test:

• New drugs or biologics (antibodies, vaccines, gene therapies)
• New combinations of existing drugs
• New surgical procedures or devices
• New approaches to radiation therapy
• Behavioral and lifestyle interventions
• Screening and diagnostic tests
• Preventive interventions in healthy populations

Clinical trials are distinct from observational studies (which observe participants without assigning interventions) and from case series or anecdotal reports. The distinguishing feature is that participants are assigned to interventions by the researchers.