In regards to decision making for reirradiation of a recurrent intramedullary spinal cord metastasis.

high doses could lead to more rapid pain relief and prolonged cancer control. Studies have demonstrated the usefulness of this technique in treating paraspinal tumors with high rates of local control and complete pain response (16). In SBRT for vertebral metastases, the use of highly conformal radiotherapy, stereotaxis, and patient immobilization allows for a steep dose gradient between the vertebral target and the adjacent spinal cord segment, reducing the reirradiation exposure to that segment (17). This is juxtaposed against the treatment of an intramedullary tumor, where no meaningful separation exists between the tumor and normal cord. Additionally, the highest dose regions (so called “hot spots”) are likely to occur within the GTV or PTV, which is situated within the cord in intramedullary tumor reirradiation versus in the bone in the case of vertebral metastasis treatment. Consequently, reirradiation of an intramedullary tumor is significantly more difficult and more fraught with risk when compared to that of a vertebral metastasis. The few small studies that have examined SBRT for intramedullary metastases have reported relatively favorable results, though. The Stanford experience reviewed nine patients treated with a median 21Gy in 3 fractions, and with a median survival of 4.1 months, Jour. of Radiosurgery and SBRT, Vol. 3, pp. 165–168 © 2014 Old City Publishing, Inc. Reprints available directly from the publisher Published by license under the OCP Science imprint, Photocopying permitted by license only a member of the Old City Publishing Group.