What is the rate of dementia following whole brain radiotherapy in patients with brain metastases who survive for over a year?

To answer this question we need to have a common understanding of "dementia." I think that those of us who follow patients long-term after WBRT all agree that there are cognitive changes that develop. From the placebo arm of RTOG 0614 we know that at 6 months 65% of patients experienced cognitive dysfunction as measured by the RTOG battery of cognitive tests. This was reduced to 54% in the memantine arm. Both of those numbers remained basically stable at one year although the number of survivors by that point were very small. So over half of one-year surivivors receiving WBRT and memantine for 6 months will still experience cognitive decline. Cognitive decline and dementia are not necessarily equivalent, however. MMSE, which arguably is a m...