I know this is a three year old question, but for anyone who is looking at this in the future - the answer to the shadowing question is yes. There are a lot of opportunities through the program to shadow doctors either in the surgery department at St. Jude, or at various locations of the West Cancer Center in Memphis. You can also independently organize something with a doctor while you're there. I'm not sure about volunteering, but there's a great volunteering program at St. Jude and I'm sure you could ask either them or someone within the POE program itself.