Update of human spinal cord reirradiation tolerance based on additional data from 38 patients
- Department of Radiation Oncology, Klinikum rechts der Isar der Technischen Universitaet Muenchen, Munich (Germany)
Purpose: To update a combined analysis of all published clinical data. Methods and Materials: We collected data from 38 additional patients treated in our department or published in four different reports and calculated the biologically effective dose (BED) according to the linear-quadratic model using an {alpha}/{beta} value of 2 Gy for cervical and thoracic cord and 4 Gy for lumbar cord. In this model, a dose of 50 Gy given in single daily fractions of 2 Gy is equivalent to a BED of 100 Gy{sub 2} or 75 Gy{sub 4}. Results: The 2005 risk score based on three variables (cumulative BED, highest BED of all treatment series in a particular individual, and interval), which discriminate three different risk groups, does not require modification. The low-risk group now contains 1 case of radiation myelopathy (RM) after hypofractionated stereotactic reirradiation. Therefore, the rate increased from 0% to 3%. Intermediate-risk patients developed RM in 25%, and high-risk patients in 90%. When the interval between the two treatment courses is not shorter than 6 months and the dose of each course is {<=}98 Gy{sub 2}, the cumulative BED where no case of RM has yet been reported is 120 Gy{sub 2}. Conclusions: Based on these updated results, the risk of RM appears small after {<=}135.5 Gy{sub 2} when the interval is not shorter than 6 months and the dose of each course is {<=}98 Gy{sub 2}. We would recommend limiting the dose to the lowest feasible level. The influence of very steep dose gradients from stereotactic and intensity-modulated approaches (i.e., a more complex volume-effect) requires further evaluation.
- OSTI ID:
- 20850269
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 66, Issue 5; Other Information: DOI: 10.1016/j.ijrobp.2006.07.1383; PII: S0360-3016(06)02772-6; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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