I post this with trepidation.
I am not suggesting anything more than possible risk reduction. I know it sounds mundane but have you considered diet and particularly looking at balancing the omega threes and sixes.
It is reported that approximately 60% of the brain is made up of "fat" of which a significant proportion is DHA (long chain omega three)
In a book called Smart fats A Schmidt p146 it is suggested that DHA was low and omega six high in brain tumour tissue. The book cites three trial references. Page 146
Together with a book on depression The Natural Way to Beat Depression by Dr Puri it makes thought provoking reading as to the importance of fats to brain health and function.
There are lots of posts on this site on omega three and six.
Here is one link.
http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum
I must stress how important it is to talk to your advisors about any significant dietary changes. I cannot advise you I am just trying to draw attention to observations of others in case of interest.
I hope whatever pathway you choose with your advisors after your deliberations helps you to health.
RB