Vitamin D for Treatment of Glioblastoma Multiforme

Inclusion Criteria: 1. Age \> 18 years 2. Newly-diagnosed, histologically confirmed GBM 3. Surgical procedures: craniotomy with gross tumour resection or maximal debulking 4. Brain lesion suitable suitable for radical 3-DCRT/IMRT according to tumour location and size. 5. Karnofsky performance status (KPS) \> 70 (ECOG/WHO 0-1) 6. No previous RT to brain 7. No serious comorbid condition 8. No treatment with biological response modifiers or cytotoxic agents within four weeks prior to study entry 9. No participation in clinical trial using any investigational drug or device within four weeks prior to study entry 10. No serious complication of malignant condition 11. No previous or concurrent malignancy at other sites, except cone biopsied in situ carcinoma of the uterine cervix and adequately treated basal cell or squamous cell carcinoma of the skin 12. Adequate organ function as evidenced by the following peripheral blood counts or serum chemistries at study entry: * Hemoglobin \> 9.0 Gm/dL * WBC count \> 4.0x109/L * Neutrophile count \> 1.5 cells x 109/L, * Platelet count \> 100 x 109/L, * Creatinine \< 1.5 mg/dL * Total bilirubin \< ULN (upper limit of normal) * AST/SGOT \< ULN * Calcium \< ULN 13. Ability to sign informed consent 14. Ability to attend follow-up visits Exclusion Criteria: 1. Surgical procedures: only stereotactic biopsy 2. Brain lesion not suitable for 3-DCRT/IMRT 3. KPS \< 70 (ECOG/WHO \<2) 4. Previous RT to brain 5. Treatment with biological response modifiers or cytotoxic agents within four weeks prior to study entry 6. Participation in clinical trial using any investigational drug or device within 7 weeks prior to study entry 7. Major surgical procedure within two weeks prior to study entry 8. Serious comorbid condition, inclusive but not limited to myocardial infarction within previous six months, uncontrolled cardiac arrhythmias, uncontrolled angina pectoris, active infection including acute hepatitis 9. Serious complication of malignant condition 10. Previous or concurrent malignancy 11. Known hypersensitivity to vitamin D 12. Inadequate organ function as evidenced by the following peripheral blood counts or serum chemistries at study entry: * Hemoglobin \< 9.0 Gm/dL * WBC count \< 4.0x109/L * Neutrophile count \< 1.5 cells x 109/L, * Platelet count \< 100 x 109/L, * Creatinine \> 1.5 mg/dL * Total bilirubin \> ULN (upper limit of normal) * AST/SGOT \> ULN * Calcium \> ULN 13. Inability to sign informed consent 14. Psychological, familial, sociological or geographical conditions which do not permit regular medical follow-up and compliance with the protocol.