Before cancer treatments can be generally prescribed, the treatment is tested in various types (or phases) of clinical trials.  A treatment must pass through a number of steps before it can be approved by the Food and Drug Administration (FDA) for widespread use.

 

Phase I: This phase of cancer research involves a small number of people, generally between 15 and 30 people.  Patients who have already unsuccessfully taken standard treatments, and are without other effective cancer treatment options are eligible to participate.  Phase I trials are used to asses the safety of a treatment or medication.  It helps find the safest dose of a new drug, at which level it will not cause adverse side effects in the patients.  It also examines which mode of administration is most effective (oral vs. intravenously).

 

Generally, patients in Phase I trials are divided into small groups of patients (cohorts) which usually include approximately between three to five people.   The first cohort receives a low, introductory dose of the new drug.  Usually, researchers periodically conduct various tests throughout the trial to measure drug levels in the patients.  If no severe side effects are apparent, a second cohort receives the same drug in an elevated dose.  The dose increases with each subsequent cohort until an optimum dosage is determined or too many adverse effects occur.

 

If the results are satisfactory, the treatment is tested again in a Phase II format.

 

Phase II:  A small number of patients are also involved in this phase of cancer research, with usually less than 100 participating.  Patients who volunteer for these trials may have been previously treated with chemotherapy, biotherapy, surgery or radiation, and still need further treatment.  Phase II clinical trials test the treatment to see if it will work against a certain kind or subtype of cancer.  Side effects are still monitored and recorded by doctors.  

 

If this treatment is effective against cancer in a certain percentage of patients, the treatment moves on to Phase III.

 

Phase III: This phase of cancer research involves hundreds, sometimes thousands, of people.  The goal of this phase is to compare the new treatment to the currently best known treatment.  Researchers observe whether a new treatment is better, the same, or less effective than the standard treatment.  Phase III clinical trials usually consist of two or more arms (groups), and a patient has equal opportunity of participating in any one of these (called randomization, used to avoid statistical bias).  One group usually receives a standard treatment – known as the control group; and the other receives the experimental treatment – known as the investigational or experimental group. 

 

Phase IV trials find additional information about a new treatment that has already been approved for use in human subjects.  This usually looks at the effectiveness or side effects of treatments over a long period of time.