What is the Purpose of Clinical Trials?

The goals of different phases of clinical trials

What is the purpose of clinical trials and what do you need to know if you are considering one of these studies? Clinical trials are surrounded in a bit of mystery, and many people become anxious about enrolling.

Learn about the different types of trials, the goals of phase 1, phase 2, phase 3, and phase 4 trials, and how clinical trials are changing with advances in targeted therapies and immunotherapy so that sometimes an early stage clinical trial may be the best option for survival.

Scientist pipetting samples into eppendorf tubes
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Overall Purpose of Clinical Trials

The purpose of clinical trials is to find ways to more effectively prevent, diagnose, or treat disease. Every drug and procedure that is used in cancer treatment was once studied as a part of a clinical trial.

Myths about clinical trials abound—such as you will be essentially a human guinea pig. But it can be helpful to understand that any approved treatment you will receive as a standard of care was once studied in a clinical trial and found to be superior or have fewer side effects than whatever had been used prior to that time.

While the purpose of clinical trials in medical research has not changed much in recent years, there are important—and mostly unspoken—changes taking place in the role of the individual patient participating in these trials. We will discuss that further below, after discussing the more specific purpose of different types and phases of clinical trials.

Types of Clinical Trials

The purpose of different trials varies depending on the question that is being asked as part of the study. Different types of clinical trials include:

  • Preventive trials: These trials study ways to prevent a disease or a complication of a disease from occurring.
  • Screening trials: Screening trials look for ways to detect a cancer at an earlier more treatable stage. For example, trying to find a way to detect lung cancer at an earlier stage than it is usually diagnosed. They are also called early detection trials.
  • Diagnostic trials: The trials look for better and less invasive ways to diagnose a cancer.
  • Treatment trials: People are often most familiar with treatment trials, the studies that look for medications and procedures that work better or are tolerated better with fewer side effects.
  • Quality of life trials: Trials looking for better ways of providing supportive care for people with cancer are very important and becoming more common.

Phases of Clinical Trials

In addition to being a study of a certain type, clinical trials are broken down into phases including:

  • Phase 1 trials: These trials are conducted on a small number of people and are designed to see if a treatment is safe. Phase 1 trials are conducted on people with different types of cancer.
  • Phase 2 trials: After a treatment is considered to be relatively safe, it is evaluated in a phase 2 trial to see if it is effective. Phase 2 trials are conducted on people with only one type of cancer.
  • Phase 3 trials: If a treatment is found to be relatively safe and effective, it is then evaluated in a phase 3 trial to see if it is more effective than standard treatments available, or has fewer side effects than standard treatments. If a drug is found to be more effective or safer in a phase 3 trial, it may then be evaluated for FDA approval.
  • Phase 4 trials: Usually a medication is approved (or not approved) by the FDA on completion of a phase 3 trial. Phase 4 trials are done after FDA approval mainly to see if side effects occur over time in people who are taking the drug.

Changing Purpose for Individuals

As noted earlier, while the purpose of clinical trials in medicine has not changed, there is an unspoken way in which these trials are indeed changing for individual participants—a change that is corresponding with our improved understanding of the genetics and immunology of tumors. There are two different ways in which clinical trials are changing.

For many years, the predominant type of trial has been the phase 3 trial. These trials usually evaluate large numbers of people to see if a treatment may be better than a previous treatment.

With these trials, there is sometimes little difference between the standard and the experimental treatment. The clinical trial drug is probably relatively safe having gotten to this point, but there is not necessarily a great chance that it will work significantly better than the older treatments.

In contrast, there has been an increasing number of phase 1 trials done for cancer in recent years. These, as noted, are the first studies done on humans, after a drug has been tested in the lab and perhaps in animals.

These treatments certainly carry more risk as the primary goal is to see if a treatment is safe, and only a small number of people are included in these studies.

Yet there is often more potential—at least given the types of treatments that are currently entering trials—that these treatments may offer a chance for survival much more dramatic than was possible in the past. ​For some people these drugs have offered the only chance of survival, as no other drugs in a new category have yet been approved. 

You may think this sounds a little like the lottery, but this has changed as well in recent years. Years ago a phase 1 trial may have been more of a stab in the dark, looking for anything to treat the cancer.

Now, many of these drugs are designed to target particular molecular processes in cancer cells that have been tested for in those who would receive the drugs in clinical trials. In other words, the second primary way in which clinical trials is changing is largely responsible for the first.

The human genome project has opened many new doors and avenues, allowing researchers to design targeted drugs that directly target specific and unique abnormalities in a cancer cell. In addition, immunotherapy is allowing researchers to find ways to supplement and harness our own body's ability to fight cancer.

Need for Clinical Trial Participation

The previous lengthy explanation of the change in clinical trials can hopefully reduce some of the fear about clinical trials. Not only are clinical trials able to move medicine forward, but due to important changes in the way we treat cancer, carry the potential to benefit individual people with cancer more than ever before. 

That said, it's thought that only 1 in 20 people with cancer who could possibly benefit from a clinical trial are enrolled. Talk to your oncologist. Learn about clinical trials. This may seem overwhelming, but several of the large lung cancer organizations have formed a free clinical trial matching service. Make sure to be your own advocate in your care.

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