Inclusion Criteria:

- Pathological diagnosis of chondrosarcoma of the spine or sacrum or chordoma of the
base of skull, spine or sacrum. Pathologic diagnosis to be confirmed at MGH or other
participating institution.

- Participants need not have measurable disease. Lesion may be primary or recurrent
after prior surgery. Patient tumor status: 1) Status post biopsy only and no further
surgery planned, 2) Status post resection with gross residual disease, 3) Status post
grossly complete research but with margins positive or close (10mm or less), 4)
Status post biopsy and patient to have additional surgery and radiation

- No prior radiation treatment to the affected skull base, spine, or sacral region.
Prior chemotherapy is allowed within 30 days of start of treatment

- 18 years of age or older

- ECOG Performance Status of 0, 1 or 2

- NOrmal organ and marrow function as outlined in the protocol

- No clinical, radiographic or other evidence of distant metastasis

- Women of child-bearing potential and men must agree to use adequate contraception
prior to study entry and for the duration of study participation

Exclusion Criteria:

- Participants may not be receiving any other investigational agents

- Participants with metastases

- Evidence of brainstem/cord/cauda or other neuromuscular or neurosensory malfunction
from causes other than effects of local tumor growth or metabolic effects of tumor

- Uncontrolled intercurrent illness including, but not limited to ongoing or active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance with
study requirements. Disease/conditions characterized by high radiation sensitivity.
These include genetic diseases, such as ataxia telangiectasia

- Pregnant women

- Individuals with a history of a different malignancy are ineligible except for the
following circumstance. Individuals with a history of other malignancies are
eligible if they have been disease-free for at least 5 years and are deemed by the
investigator to be at low risk for recurrence of that malignancy. Individuals with
the following cancers are eligible if diagnosed and treated within the past 5 years:
cervical cancer in situ, and basal cell or squamous cell carcinoma of the skin.

- HIV-positive individuals on combination antiretroviral therapy