Welcome to the club Mrhappy, sorry are here but since you are be sure to get your money's worth. As for doubling time I would think with your low grade it would be a long time. I will not say not to worry about it because it is cancer, however I would right now turn my attention to learning as much as you can about this disease so you can make an informed decision as to how to combat it.
I look forward to your posts please keep us posted as to your decisions and please ask us for any information.
peace and love