Cancer Basics

Cancer and Clinical Trials

You’ve probably heard of clinical trials; they are talked about a lot in cancer care. Read more to understand how clinical trials work, what the different phases are, and who may be eligible to participate.

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What are clinical trials?

Clinical trials are research studies that help doctors learn whether a new drug or treatment works and is safe to use. They help advance our knowledge of cancer and are an important part of developing new treatments. If you or a loved one needs treatment for cancer, clinical trials may be an option to consider.

Clinical trials may test new ways to:

  • Detect and prevent cancer
  • Treat cancer
  • Manage symptoms of cancer and side effects from treatment

There may be clinical trial options across all stages of cancer, from early to advanced.

As a result of past clinical trials, people living with cancer today have more treatment options. When you take part in a clinical trial, you help researchers learn more about cancer and that helps improve cancer care for people in the future. You also help researchers understand if new treatments are more effective than the current ones.

Clinical trials are a key part of developing new cancer treatments

How do clinical trials work?

Clinical trials are the last steps in a long process that starts in the research lab. Researchers work for many years to understand how a new treatment affects cancer cells in the lab before it is used on people in clinical trials. During this time, they are also learning about the potential side effects of the new treatment as well.

All new treatments must go through several steps or phases of testing and clinical trials before they are approved by the Food and Drug Administration (FDA).

If a potential treatment is successful in one phase, it will move to the next one. Here are the four major clinical trials phases:

Phase I trials


During this first phase, which may last less than 18 months, researchers test the possible side effects of an experimental treatment on a small, select group of volunteers.

In this phase, researchers are assessing how the patient’s body handles the medicine. They are also:

  • Finding the appropriate safe dose for people
  • Deciding on the best delivery method of the medication (for example oral, by injection into the veins, or by infusion)
  • Recording any side effects patients experience 

Phase II trials


In this next phase, the drug or treatment is tried on a larger group of people (usually around 100 patients). This phase can last around two years.

The purpose of Phase II is to determine the effect the treatment has on a disease, like cancer, and to see how the treatment impacts the rest of the body.

Phase III trials


In this phase, the experimental treatment is tried by large groups (up to several thousands) of patients.

This phase helps researchers discover how effective the new drug is compared to the standard treatments already available.

Once Phase III is complete, a drug manufacturer will file a new drug application with the FDA. Then, the FDA reviews all the research on the drug or treatment and determines whether they will approve it for public use.

If approved, the drug manufacturer can release the product for use in patients by doctors.

Phase IV trials


After the product is approved for the public, Phase IV studies provide more information about long-term risks and benefits. These studies help researchers understand how the drug or treatment should be optimally used.

Visit ClinicalTrials.gov for more information.

Who can join a clinical trial?

Most often, researchers are looking for a specific type of patient in each study. Clinical trials have protocols that describe the specifications for the people who can participate in the study. That description is called “eligibility criteria,” and clinical studies can only include people who meet these established requirements.

Eligibility criteria are different for each trial and are used to identify who is most appropriate for the trial. All studies are different. Some studies include healthy volunteers, while other studies only include patient volunteers. There are studies that include both healthy and patient volunteers. Most studies today try to include a diverse set of people since medications affect various populations in different ways. To test a new treatment, researchers usually need people of all races, ethnicities, and sexes. However, there may be age restrictions, depending on how the treatment is designed.

Researchers will specify the eligibility criteria that determine which patients are able to participate in the study. Not everyone is eligible for every study, even if you might be interested in participating.

Interested in joining a clinical trial?

Learn how to find one and what you need to consider about joining. Remember, always talk to your doctor about your treatment decisions.

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