If you can, get the name of the trial and do some research on it, get a second opinion (this you have to do) ask the Dr why he wants you to do it and then decide. I'm always cautious when being pushed towards a trial as sometimes the center or Dr may be being paid to get patients into one (Doesn't mean its a bad trial, but doesn't always mean its the best thing for you.).
My onc was pushing me to get into a trial, but after research (including here) I found it had mixed to poor results to date and I declined. 6 months later, the posted results have not shown any improvement and even my onc has admitted it isn't the holy grail they had hoped.