A Phase 3 trial is the final stage of testing before a medication or other type of medical treatment can potentially be approved for widespread use. Phase 3 trials involve large numbers of people — typically hundreds in each group. Some study participants may be concerned that they will be put in the group that only receives a sham treatment, known as a placebo. The classic example of a placebo is a "sugar pill," a pill given to a study participants that contains no active ingredients.
Sugar pills are not an option for life-threatening diseases like breast cancer
In a scientific study, the ideal comparison to a treatment is an absence of any treatment. Often in a clinical trial, effectiveness is measured against a placebo, or against another type of comparison. In the case of life-threatening diseases such as breast cancer, it is not acceptable to use no treatment as a comparison, so comparisons are commonly made using a different drug or treatment -- one that is already approved for use.
A comparison is needed to understand that the new medication or treatment works (efficacy) and also to see that the treatment is safe (adverse events). Researchers will design the breast cancer clinical trial for a specific period of time, during which participants either get the study treatment or the comparison treatment.
When might a placebo be used?
There may be rare instances in which a placebo is used, and that is when another treatment already exists and is known to work. In this case, the regular treatment would be given to both groups, and the experimental treatment is added on to the comparison as an extra treatment (add-on therapy). The comparator group will then get the standard treatm