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Multiple sclerosis, brain radiotherapy, and risk of neurotoxicity: the Mayo Clinic experience
Robert C Miller1, Daniel H Lachance, Claudia F Lucchinetti
1Department of Radiation Oncology, Mayo Clinic, Rochester, MN55905, USA. miller.robert@mayo.edu
Purpose:
The aim of this study was a retrospective assessment of neurotoxicity in patients with multiple sclerosis (MS) receiving external beam radiotherapy (EBRT) to the brain.
Methods And Materials:
We studied 15 consecutively treated patients with MS who received brain EBRT. Neurologic toxicity was assessed with the Common Toxicity Criteria v.3.0.
Results:
Median follow-up for the 5 living patients was 6.0 years (range, 3.3-27.4 years). No exacerbation of MS occurred in any patient during EBRT. Five patients had Grade 4 neurologic toxicity and 1 had possible Grade 5 toxicity. Kaplan-Meier estimated risk of neurotoxicity greater than Grade 4 at 5 years was 57% (95% confidence interval, 27%-82%). Toxicity occurred at 37.5 to 54.0 Gy at a median of 1.0 year (range, 0.2-4.3 years) after EBRT. Univariate analysis showed an association between opposed-field irradiation of the temporal lobes, central white matter, and brainstem and increased risk of neurotoxicity (p < 0.04). Three of 6 cases of toxicity occurred in patients treated before 1986.
Conclusions:
External beam radiotherapy of the brain in patients with MS may be associated with an increased risk of neurotoxicity compared with patients without demyelinating illnesses. However, this risk is associated with treatment techniques that may not be comparable to modern, conformal radiotherapy.
