RATIONALE: Specialized radiation therapy, such as proton beam radiation therapy, that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue.

PURPOSE: This phase I/II trial is studying the best way to give proton beam radiation therapy and to see how well it works in treating patients with low grade gliomas.

PRIMARY OBJECTIVES:

I. To evaluate the feasibility of proton beam radiation therapy in patients with low grade gliomas. (Phase I)

SECONDARY OBJECTIVES:

I. To assess late complications from irradiation using proton beam therapy in place of conventional photon beam therapy for the treatment of low grade gliomas. (Phase II) II. To assess acute side effects from irradiation using proton beam therapy in place of conventional photon beam therapy for the treatment of low grade gliomas. (Phase II) III. To compare the dose distribution to tumor and surrounding normal structures using DVH's (Dose Volume Histograms) generated from the proton plan used to treat the patient and the photon plan generated for comparison purposes. (Phase II) IV. To monitor the rates of local control, overall and disease specific survival using proton radiotherapy. (Phase II) V. To evaluate the time to progression of low grade gliomas treated with protons. (Phase II) VI. To evaluate the incidence and severity of fatigue in low grade glioma treated with protons. (Phase II) VII. To evaluate the effect of proton beam radiation on neurocognitive outcome in patients with low grade glioma. (Phase II) VIII. To evaluate the quality of life in patients treated for low grade glioma. (Phase II)

OUTLINE: Patients undergo proton beam radiation therapy for 6 weeks in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed periodically for 5 years.

Inclusion

• Patients with histologically confirmed diagnosis of low grade glioma of the CNS

• Patients with WHO grade II; may be symptomatic; including patients who are being followed and have radiographic expression

• Patients must have a Karnofsky Performance Status of >= 60

• Patients must be able to provide informed consent

• Patients must have adequate bone marrow function:

  1. WBC >= 4000/mm^3
  2. platelets >= 100,000 mm^3

• Women of child-bearing potential as long as she agrees to use a recognized method of birth control (e.g. oral contraceptive, IUD, condoms or other barrier methods etc); Hysterectomy or menopause must be clinically documented

Exclusion

• Patients who have had prior or simultaneous malignancies within the past two years (other than cutaneous squamous or basal cell carcinoma, melanoma in situ or thyroid carcinoma)
• Patients with the following histologies:

gliomatosis cerebrei, WHO III or IV gliomas

• Patients who have had any prior Radiation treatment
• Patients who have had any chemotherapy administered within 30 days of the planned radiation treatment start date
• Pregnant women, women planning to become pregnant and women that are nursing
• Patients who are actively being treated on any other therapeutic research study