Hi AJG,
Participation in trials is voluntary so if youre not comfortable, make sure you let them know thAt!
The first couple of weeks are the worst scariest time. It does calm down a little bit. If you don't understand anything, ask your doctor to stop and explain it and write down anything you think is important.
Also don't be afraid to ask them to explain your pathology and what it means and if it is good or bad. It's your body and you should be 100% comfortable with what they are doing to it!