Adult PNET

My wife has a golf ball sized malignant level 4 tumor in her thalamus region. We have had a shunt implanted to relieve fluid build-up because the tumor is pressing on the 3rd ventricle. We are getting conflicting advice on treatment strategys from her doctors. Focal radiation to treat just the tumor ( both full spinal MRI & spinal tap were clean ) vs. cranial-spinal radiation which is supposedly important to contain the spread or recourance of cancer. Also the use of viscristine during radiation to limit the effects of white blood cell counts. Medical oncologist fears nerve damage due to the differences between adult bone marrow vs. children. ( average age for a PNET is 9 ) Any constructive thoughts on how to get the doctors on the same page or is that just wishful thinking ?