Clinical Trials: What You Need to Know

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Why do we need clinical trials?

Clinical trials show us what works (and what doesn’t) in medicine and health care. They are the best way to learn what works best in treating diseases like cancer. Clinical trials are designed to answer 2 important questions:

  • Does the new treatment work in humans? If it does, doctors are also looking at how well it works. Is it better than what’s now being used to treat a certain disease? If it’s not better, is it at least as good, while perhaps causing fewer side effects? Or does it work in some people who aren’t helped by current treatments? In other words, is it a step forward? A treatment that doesn’t offer anything new probably isn’t worth studying.
  • Is the new treatment safe? This must be answered while realizing that no treatment or procedure – even one already in common use – is entirely without risk. But do the benefits of the new treatment outweigh the possible risks?

Answering these questions, while exposing as few people as possible to an unknown treatment, often requires several different clinical trials. They are usually grouped into “phases.” Clinical trials in each phase are designed to answer certain questions, while trying to make sure the people taking part are kept as safe as possible. Every new treatment is tested in 3 or more phases of clinical trials before being considered reasonably safe and effective. These phases are discussed in the section called “What are the phases of clinical trials?

New treatments have to pass many tests before they get to you.

Clinical trials are only a small part of the research that goes into developing a new treatment. Drugs of the future, for example, first have to be discovered or created, purified, described, and tested in labs (in cell and animal studies) before ever reaching human clinical trials. Of all the substances that are tested in these early stages, very few are promising enough to be tested in humans.

On average, a new cancer drug has been studied for at least 6 years before it even makes it to clinical trials. But the major holdup in making new cancer drugs available is how long it takes to complete clinical trials themselves. It takes an average of about 8 years from the time a cancer drug enters clinical trials until it’s approved.

Why so long? To be sure it’s safe and effective, researchers look at each new treatment in several different studies. Only certain people are eligible (meet the requirements) to take part in each clinical trial. And cancer clinical trials take years to complete. It takes months, if not years, to see if a cancer treatment works in any one person. And figuring out if a drug really improves survival can take a very long time.

The biggest barrier to completing clinical trials is that not enough people take part in them. Fewer than 5% of adults (less than 1 in 20) with cancer will take part in a clinical trial, while 60% of children under age 15 do. This is one reason that survival rates for childhood cancer have increased so dramatically in the last few decades. The main reason people give for not taking part in a clinical trial is that they didn’t know the studies were an option for them. But there are many other reasons. Some people want to take part but don’t meet the requirements. Some are uncomfortable with the idea of being a volunteer in a study. Others worry that they won’t be treated fairly or could be harmed by an unproven treatment. All of these are valid concerns and are covered in more detail in the section called “Should I think about taking part in a clinical trial?


Last Medical Review: 09/25/2014
Last Revised: 10/31/2014