I. Determine the origin of the cells which form the capillary structure which supports the regrowth of tumor post radiation.
II. Understand the mechanism for the marked difference in tumor control probability following radiation treatment of chrondosarcoma and chordoma.
III. Assess the proportion of patients with distant metastasis and local regrowth of tumor whose distant metastasis arise from the regrowing tumor.
IV. Time distribution of radiation induced neoplasms as function of radiation dose and of chemotherapeutic agents.