PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy and recovered No concurrent biologic therapy Chemotherapy: At least 4 weeks since prior chemotherapy and recovered No prior carboplatin and temozolomide No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: At least 4 weeks since prior radiotherapy and recovered At least 3 weeks since prior palliative radiotherapy No concurrent radiotherapy Surgery: No concurrent surgery to tumor Other: No other concurrent investigational agent