Radiation dose-volume effects in the spinal cord.
Dose-volume data for myelopathy in humans treated with radiotherapy (RT) to the spine is reviewed, along with pertinent preclinical data. Using conventional fractionation of 1.8-2 Gy/fraction to the full-thickness cord, the estimated risk of myelopathy is <1% and <10% at 54 Gy and 61 Gy, respectively, with a calculated strong dependence on dose/fraction (alpha/beta = 0.87 Gy.) Reirradiation data in animals and humans suggest partial repair of RT-induced subclinical damage becoming evident about 6 months post-RT and increasing over the next 2 years. Reports of myelopathy from stereotactic radiosurgery to spinal lesions appear rare (<1%) when the maximum spinal cord dose is limited to the equivalent of 13 Gy in a single fraction or 20 Gy in three fractions. However, long-term data are insufficient to calculate a dose-volume relationship for myelopathy when the partial cord is treated with a hypofractionated regimen.
Kirkpatrick
John P
JP
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA. jkirk@radonc.duke.edu
van der Kogel
Albert J
AJ
Schultheiss
Timothy E
TE
D000367:Age Factors; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D011832:Radiation Injuries / Q000209:etiology*; D011836:Radiation Tolerance; D016634:Radiosurgery / Q000009:adverse effects; D011878:Radiotherapy / Q000009:adverse effects; D051381:Rats; D019233:Retreatment / Q000009:adverse effects; D013116:Spinal Cord / Q000528:radiation effects*