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Doctors often suggest that patients take part in clinical trials to gain access to promising treatments and medications. Trials are grouped into four phases:

  • Phase I trials involve a small number of people and help assess the safety of a new treatment or determine an effective drug dose.
  • Phase II trials focus on the effectiveness of a treatment and usually involve fewer than 100 participants.
  • Phase III trials compare a new treatment with standard treatments. This can involve adding a new drug to a proven therapy to determine if the combination is more effective. The size of these trials ranges from hundreds to thousands of participants.
  • Phase IV trials gather information about treatments that have already been approved by the FDA for use in patients.

Randomized, double-blind phase III trials are considered the gold standard because of the large number of participants, the random assignment of patients to one treatment or another, and the fact that neither the doctor nor the patient knows which therapy is being used. In some cases, the treatment is actually a placebo, an inactive pill or procedure designed to look like the real one. Patients should know whether or not they are taking part in a placebo-controlled study, as there is often a sizable chance that they will not be receiving an active treatment. The possibility that you will receive a placebo instead of an active treatment is one drawback of enrolling in a clinical trial.

Clinical trials benefit thousands of people every year, but your decision to enroll should not be a purely altruistic one. Get as much information as you can by asking questions such as these:

  • Why is the study being done?
  • Have other studies evaluated this drug or procedure? What were the results?
  • Is there a chance that I will receive a placebo?
  • What are the possible risks and benefits of participating?
  • What other treatment options do I have?
  • What treatments, tests, and medical procedures will I receive?
  • Can I continue to take my regular medications?
  • How long will the study last?
  • Will I have to pay for any treatments or tests?
  • If the investigational drug or treatment works for me, can I continue to receive it when the trial ends?
  • Who will be responsible for my care?
  • How might my participation affect my daily routine? Will I miss work?
  • Does the study involve a hospital stay?

If a doctor asks you to volunteer for a clinical trial, you do not need to say yes. Ask questions and then decide what makes sense for you. If you say no, your care at the hospital and your relationship with your doctor will not be affected. If you agree to join the study and later change your mind, you are free to stop participating. Be sure to ask what care you will receive if you leave the study before it concludes.

When you enroll in a trial, the "protocol" should be explained to you. The protocol details how the trial will be conducted. You should receive the name and phone number of the doctor in charge of the study, as well as a phone number to call if you have any questions related to your safety. (Clinical trials are designed to minimize risks to volunteers, but they cannot completely eliminate them.) You should also receive a copy of your signed consent form.

Clinical trials currently enrolling patients, along with enrollment criteria, are listed online at After you navigate to this page, you can search by medical condition and other criteria. Cancer patients can also call the National Cancer Institute's Clinical Trials Referral Office at 888-624-1937 (toll-free) for information.

Last Annual Review Date: 2011-01-01T00:00:00-07:00 Copyright: Copyright Harvard Health Publications

Reference: Cancer section on Better Medicine

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