Treatment on this study combines two drugs: Thalomid™ (thalidomide) and carboplatin. Thalidomide has been available for many years and has been used to treat many different illnesses. Carboplatin is an effective medicine in killing cancer cells. Thalidomide works by blocking angiogenesis (the process of new blood vessel formation). If a tumor does not have blood vessels providing oxygen and nutrients, it will not be able to grow. This research will look at how combining the effects of thalidomide (preventing tumor growth) with the tumor killing effect of carboplatin effects the long-term outlook for patients with these tumors.

This study will try to find out how well Thalomid™ and carboplatin combined with radiation therapy works in treating children newly diagnosed with brain stem glioma. This study will look at how well Thalomid ™ and carboplatin work in patients with recurrent brain stem glioma. This study will also look at any side effects of these treatments.

Inclusion Criteria:

• Patients must be >/= 3 and </= 21 years of age.
• Patients must have a newly diagnosed or progressive brain stem tumor.
• If biopsy has been performed, patients with both high and low grade astrocytomas are eligible.
• Non-histologically confirmed brain stem tumors are eligible. Neuroradiographic confirmation of brain stem glioma is mandatory for study entry.
• Cervicomedullary junction tumors are ineligible.
• Patients with a diagnosis of NF-1 are ineligible.
• Patients must be registered within 6 weeks from diagnosis or recurrence.
• Patients must have life expectancy > 6 weeks.
• Patients must have adequate hematologic and renal function: ANC >1,000/ul, platelets>100,000/ul and creatinine normal for age: \