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 for 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, “What are the phases of clinical trials?

How long have clinical trials been used?

Some doctors and scientists conducted what would now be thought of as clinical trials as far back as the late 1700s, but clinical trials were not used widely until the middle of the 20th century. Up until that time, doctors relied on their own experience in similar cases and on the teachings of those who came before them. Progress was slow, and very few medicines were available to even be tested.

With the discovery of the first antibiotics and other drugs, doctors needed a reliable way to tell what worked from what didn’t. They also needed ways to find out which of the countless remedies available at that time were safe for people to use. So they came up with ways to test and compare treatments in certain groups of people. The results of these early clinical trials proved to be more useful than relying on whether or not something worked for one person or a few people.

In the United States, the Food and Drug Administration (FDA) began overseeing the safety of new treatments in the late 1930s, but didn’t require proof that they actually worked until the early 1960s. Today, new drugs and medical devices must go through clinical trials before they can be approved for use. The FDA must approve new drugs and medical devices (but not dietary supplements) before they can be advertised or sold to the public.

Based on what we’ve learned about cancer in recent years, researchers can now develop new treatments in a more logical way and much faster than in the past. But it’s still a hard process that takes a long time.

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, only about 1 in 1,000 is promising enough to be tested in humans.

On average, a new cancer drug has at least 6 years of research behind it 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 is 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 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. According to the Pharmaceutical Research and Manufacturers of America (PhRMA), more than 1000 cancer medicines were being tested in clinical trials in 2012. Not all of these drugs will prove to be useful, but those that are may be delayed in getting approved because so few adults volunteer.

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 may want to take part but aren’t eligible. Some people 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. We have addressed them in more detail in the section called “Should I think about taking part in a clinical trial?


Last Medical Review: 09/21/2012
Last Revised: 09/21/2012