Inclusion Criteria:

- Patients with histologically confirmed newly-diagnosed supratentorial glioblastoma
multiforme (GBM) or gliosarcoma will be eligible for this protocol.

- The patient must have recovered from the effects of surgery, post-operative
infections and other complications before entry into the study.

- Diagnosis will have been established by biopsy or resection no more than 28 days
prior to registration.

- If tumor resection or open biopsy was performed, cranial MRI or contrast CT must have
been performed before and after surgery. Imaging within 96 h of surgery is preferred
but not required.

- If needle biopsy (stereotactic) was performed, gadolinium MRI or contrast CT within
14 days prior to registration is required. A post-operative scan is not required.
The use of MRI rather than CT is preferred. The same type of scan, i.e., MRI or CT
must be used throughout the period of protocol treatment for tumor measurement.
Patients without measurable or assessable disease are eligible.

- Patients receiving steroids must be on stable or decreasing doses for at least 5 days
prior to entry.

- Patients must have a plan to begin partial brain radiotherapy 4-7 days after
beginning lenalidomide, and within 35 days of the surgical procedure that established
the diagnosis.

- Radiotherapy must be at the Radiation Oncology Department of the registered
institution.

- Patients must be willing to forego cytotoxic and non-cytotoxic drug therapy against
the tumor while being treated with lenalidomide.

- All patients must sign an informed consent indicating that they are aware of the
investigational nature of this study.

- Patients must be > 18 years old, and with a life expectancy > 8 weeks.

- Patients must have a Karnofsky performance status of > 60.

- Patients must have adequate bone marrow, liver, and renal function.

- Patients must be willing and able to comply with all study requirements

Exclusion Criteria:

- Patient must not have had prior cranial radiation therapy.

- Patients must not have received prior cytotoxic drug therapy, non-cytotoxic drug
therapy, or experimental drug therapy for brain tumors. Patients who received Gliadel
wafers will be excluded.

- Patients must not have any significant medical illnesses that in the investigator's
opinion cannot be adequately controlled with appropriate therapy or would compromise
the patients ability to tolerate this therapy.

- Patients with a history of any other cancer (except non-melanoma skin cancer or
carcinoma in situ of the cervix), unless in complete remission and off of all therapy
for that disease for a minimum of 3 years are ineligible.

- Patients must not have active infection.

- Patients must not be pregnant/breast feeding and must agree to practice adequate
contraception.

- Patients must not have any disease that will obscure toxicity or dangerously alter
drug metabolism.

- Patients must not have serious concurrent medical illness.

- Patient with recent thromboembolic disease (deep vein thrombosis and pulmonary
embolism) are eligible if they are clinically stable and the thromboembolic event
occurred more than 2 weeks prior to enrollment into this protocol.

- Patients must not have metastases below the tentorium or beyond the cranial vault.

- Patients must not have a known diagnosis of HIV, active infectious hepatitis, or
chronic hepatitis.

- Patients must have no history of hypersensitivity or development of a desquamating
rash while on thalidomide.

- Patients must have no prior exposure to lenalidomide.

- Previous or planned stereotactic radiosurgery or brachytherapy.