Re-irradiation of the human spinal cord.
OBJECTIVE
Experimental animal data give evidence of long-term recovery of the spinal cord after irradiation. By extrapolation of these data, re-irradiation regimens were designed for eight patients who required palliative radiotherapy. As a consequence of re-irradiation, their spinal cords were exposed to cumulative doses exceeding the tolerance dose. Radiobiological and clinical data are presented.


METHODS
Eight patients were re-irradiated on the cervical (n = 1), thoracic (n = 5) and lumbar (n = 2) spinal cord. The time interval between the initial and re-treatment ranged from 4 months to 12.7 years (median: 2.5 years). (Re-)treatment schemes were designed and analyzed on basis of the biologically effective dose (BED) according to the linear-quadratic model. The repair capacity (alpha/beta ratio) for the cervico-thoracic and lumbar spinal cord was assumed to be 2 Gy and 4 Gy, with a BEDtolerance of 100 Gy and 84 Gy, respectively.


RESULTS
The cumulative irradiation dose applied to the spinal cord varied between 125 and 172% of the BEDtolerance. During follow-up, ranging from 33 days to > 4.5 years (median: 370 days) none of the patients developed neurological complications. Seven patients died from tumor progression, and one patient is still alive.


CONCLUSIONS
Long-term recovery of the spinal cord from radiation injury, which has been demonstrated in rodents and primates, may also occur in humans.
Sminia
Peter
P
Department of Radiation Oncology, Section Radiobiology, VU University Medical Center, Amsterdam, The Netherlands. p.sminia@vumc.nl
Oldenburger
Foppe
F
Slotman
Ben J
BJ
Schneider
Christoph J
CJ
Hulshof
Maarten C C M
MC
D001859:Bone Neoplasms; D001932:Brain Neoplasms; D001943:Breast Neoplasms; D002289:Carcinoma, Non-Small-Cell Lung; D002292:Carcinoma, Renal Cell; D018288:Carcinoma, Small Cell; D002574:Cervical Vertebrae; D019583:Dose Fractionation, Radiation; D005500:Follow-Up Studies; D006689:Hodgkin Disease; D006801:Humans; D007680:Kidney Neoplasms; D016014:Linear Models; D008159:Lumbar Vertebrae; D008175:Lung Neoplasms; D010166:Palliative Care; D011879:Radiotherapy Dosage; D012512:Sarcoma, Ewing; D013116:Spinal Cord / Q000528:radiation effects*; D013904:Thoracic Vertebrae; D013945:Thymoma; D013953:Thymus Neoplasms; D013997:Time Factors