How many patients typically participate in each phase of the clinical trial?

Clinical trials are often described as phase I, II, III, and sometimes phase IV.  The number of participants varies greatly depending on the phase of investigation, but also depending on the cancer type, situation, and expected outcome.  Phase I trials are principally charged with determining the safe and optimal dose of a new drug or drug combination.  Such trials may involve 20 to 40 patients.  Phase II trials are where the potential of a drug to be effective is first evaluated.  Typical phase II studies range in size from 50 to 250 participants.  The higher end of that range is more common in randomized phase II studies where 2 or more doses or drug combinations are being examined side by side.  Phase III trials are the ultimate test of a new treatment.  Participants are randomly assigned to the new treatment or the current standard.  These trials involve hundreds and sometimes thousands of participants.  The number of participants needed is determined by the question being asked, the expected magnitude of the difference between the two treatments, and the percentage of patients who are expected to experience the outcome being measured.  For example, trials that seek to reduce the risk of cancer recurrence are often very large in part because many of the participants (thankfully) don’t suffer a recurrence at all.  A large number of participants are therefore needed to make sure that enough of them have a recurrence so that a difference can be detected.

For more questions and answers about clinical trials, visit the Talk about Health website.
To put a smile on your face see Larry's latest cartoon.
To learn more about clinical trials, take a look at our book.

(c) 2012 Tom Beer and Larry Axmaker

Clinical trial phases from the participant's point of view

There are many types of clinical trials.  Most commonly, they are divided into phase I, II, III, and sometimes IV.  The phases refer to the phases of testing of a new drug in humans. Some our previous posts describe the various phases and discuss phase I trials and phase III trials in more detail.  Here we would like to share with you page 47 from our book, where we provide a succinct summary of the advantages and disadvantages of each trial type, from the perspective of trial participants.  The table shown below may not apply to every single trial, but it does give you a quick and straight forward basic guide.

If you would like to download a PDF of this page you can do so here.  Feel free to share it.

To put a smile on your face see Larry's latest cartoon.

To learn more about clinical trials, take a look at our book.
(c) 2012 Tom Beer and Larry Axmaker

The phases of cancer clinical trials

Clinical trials are often divided into phases.  These actually refer to phases in the process of developing a new drug.  Here is the scoop:

·        Phase I studies are small, and their goal is to determine the optimal dose of a drug, or combination of drugs, that can be given safely. This does not mean entirely free of side effects, just an acceptable or manageable level of side effects.

·        Phase II studies are also relatively small and may involve anywhere between 30 and several hundred patients. They are the first studies designed to test how effective a new treatment is against cancer.

·        Phase III studies are large and may involve thousands of participants. They compare the most promising new treatments to the current standard.

·        Phase IV studies usually collect more safety and effectiveness information on new therapies after the U.S. Food and Drug Administration has approved them.



To put a smile on your face see Larry's latest cartoon
(c) 2012 Tom Beer and Larry Axmaker