These trials compare new treatments to the best currently available treatment and/or placebo (the standard treatment). They may compare:
- A completely new treatment with the standard treatment
- Different doses or ways of giving a standard treatment
- A new radiotherapy schedule with the standard one
- A new device that can be tested vs. standard treatment
Phase 3 trials are usually much larger than Phases 1 or 2. Because differences in success rates may be small, many patients are needed in the trial to show the difference.
Phase 3 trials sometimes involve thousands of patients in many different hospitals, and even different countries. Generally, Phase 3 trials are required before approval of a new medication or treatment.
Systematic reviews and meta analysis
Systematic reviews are studies that combine the results of multiple Phase 2 and 3 trials of a new treatment or diagnostic tests. Another type of study that will combine research results is meta analysis. The idea is to get a broader picture of how well a treatment works and how many side effects it potentially has. The more data there is, the more accurate such studies are likely to be.