Intervention

A detailed plan of a scientific or medical experiment, treatment, or procedure. In clinical trials, it states what the study will do, how it will be done, and why it is being done. It explains how many people will be in the study, who is eligible to take part in it, what study drugs or other interventions will be given, what tests will be done and how often, and what information will be collected.

https://www.cancer.gov/publications/dictionaries/cancer-terms/def/protocol

What does "interventions" mean in the context?