Memory and survival after microbeam radiation therapy

Background: Disturbances of memory function are frequently observed in patients with malignant brain tumours and as adverse effects after radiotherapy to the brain. Experiments in small animal models of malignant brain turnout using synchrotron-based microbeam radiation therapy (MRT) have shown a promising prolongation of survival times. Materials and methods: Two animal models of malignant brain turnout were used to Study survival and memory development after MRT. Thirteen days after implantation of tumour cells, animals were submitted to MRT either with or without adjuvant therapy (buthionine-SR-sulfoximine = BSO or glutamine). We used two orthogonal 1-cm wide arrays of 50 microplanar quasiparallel microbeams of 25 mu m width and a center-to-center distance of about 200 mu m, created by a multislit collimator, with a skin entrance dose of 350 Gy for each direction. Object recognition tests were performed at day 13 after tumour cell implantation and in monthly intervals Lip 10 1 year after tumour cell implantation. Results: In both animal models, MRT with and without adjuvant therapy significantly increased survival times. BSO had detrimental effects on memory function early after therapy, while administration of glutamine resulted in improved memory.