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Understanding Clinical Trials

What Are Clinical Trials?

  • Clinical trials are research studies involving people.
  • They test ways to treat and prevent cancer.
  • All of today’s standard cancer treatments are a result of clinical trials completed many years ago.

Facts About Clinical Trials

  • More than 25,000 cancer patients enroll each year in clinical trials through the National Cancer Institute. Many more patients are enrolled in clinical trials sponsored by other groups.
  • About 60 percent of the adults enrolled in clinical trials are women.
  • Lung, breast, prostate and colon cancers have the highest number of clinical trials dedicated to them — more than 40 percent of the total number of trials.
  • Only a small percentage of all cancer patients enroll in clinical trials. Their participation may benefit them as well as future cancer patients

Who Organizes a Clinical Trial?

Organizations or individuals looking for better treatments for cancer or new ways to prevent or detect cancer may sponsor clinical trials. Individual doctors at cancer centers or other medical institutions can also conduct trials.

  • The National Cancer Institute sponsors numerous clinical trials covering a variety of cancers.
  • Other sponsors include drug makers, technology companies and groups like the American Cancer Society.
  • Each trial has a person in charge, usually a doctor, who is called the protocol chair or principal investigator (also called the PI).
  • Before enrolling in a trial, ask whether the trial has been approved by an Institutional Review Board or IRB. IRBs exist at most hospitals to help safeguard patient rights.

How Are Clinical Trials Conducted?

Clinical trials testing new treatments are carried out in phases.
Phase I — Is the Treatment Safe?
As the first step in testing the research, doctors gather information about the side effects of the treatment and decide on the safe dose. Only a few patients in a few places take part in a Phase I trial.
Phase II — Does the Treatment Work?
In this step, doctors test the treatment to see how well it works. Most of the time, fewer than 100 patients are involved in Phase II trials.
Phase III — Is the Treatment Better?
Phase III trials compare the new treatment against the current standard therapy and randomly assign patients into one of the two groups. Many people from all over the country take part in these trials.
Phase IV — Are There Better Ways to Use the Treatment?
In this final step, treatments are tested to make sure they are safe and work well over a long period of time. This phase most often occurs once the new treatment has been approved for standard use. Anywhere from several hundred to several thousand people are enrolled in a Phase IV trial.

Who Can Participate in a Clinical Trial?

Each clinical trial calls for certain criteria that a patient must meet to be included in that trial.

  • Your age, gender, medical history, current health, what type and stage of cancer all factor into eligibility.
  • It’s important to remember that clinical trials are completely voluntary. Patients can leave a trial at any time.

What Is Informed Consent?

Informed consent is the process by which you agree to take part in a clinical trial after receiving information about the purpose of the study, the treatment that will be given, the tests that will be taken, and the risks and benefits of treatment. You must sign a written consent form before being enrolled into a clinical trial. This form says that you understand the study and agree to take part.

What Are the Benefits?

Although there are risks with any treatment, there are also many benefits of taking part in a clinical trial. For example:

  • Access to promising new treatments that are not available outside of the clinical trial setting.
  • The treatment being studied may be better than the standard approach.
  • You are followed very closely by a research team that is made up of doctors and other health professionals.
  • You may be the first to benefit from the new method. Results from the study may help others in the future.

What Are the Risks?

Before taking part in a clinical trial, talk to your doctor about some of the risks involved with your treatment. For example:

  • New drugs or treatments may not be any better than the standard care they are being compared to.
  • New treatments may have side effects that are not expected.
  • If you are in a randomized trial, you will not be able to choose if you are getting the new treatment or the standard approach.
  • Health insurance may not cover all your costs.
  • You may be required to make more frequent visits to the doctor.

How Can I Join a Clinical Trial?

If you are interested in joining a clinical trial, talk to your doctor. He or she can help you find out if a trial is right for you.

  • The National Cancer Institute can give you information on current trials. Call 1-800-4-CANCER or visit to learn more.