This article posted by Lani is most interesting for members of this forum since it deals with metastatic brain cancer from breast.
It appears that Boswella Serrata might also be usefull for primary brain tumors since a phase 2 clinical trial is under preparation:
http://www.clinicaltrials.gov/ct/gui/show/NCT00243022
Boswellia Serrata Combined With a Low-Fat, Vegan Diet or a Standard Diet Alone in Treating Patients Who Have Undergone Surgery and Radiation Therapy for Newly Diagnosed Glioblastoma Multiforme