[1] Kings Coll Hosp London, Dept Neurosurg, Denmark Hill, London SE5 9RS, England
[2] Univ Oxford, Canc & Haematol Ctr, Med Stat, Dept Oncol,Churchill Hosp, Oxford OX3 7LE, England
[3] Guys & St Thomas NHS Fdn Trust, Dept Clin Oncol, London SE1 9RT, England
[4] Maidstone & Tunbridge Wells NHS Trust, Kent Oncol Ctr, Dept Clin Oncol, Hermitage Lane, Maidstone ME16 9QQ, Kent, England
[5] Kings Coll Hosp London, Dept Neuropathol, Denmark Hill, London SE5 9RS, England
[6] Kings Coll Hosp London, Dept Neuroradiol, Denmark Hill, London SE5 9RS, England