RADT-42. EFFECTS OF RADIOTHERAPY FOR CNS NEOPLASMS IN PEOPLE WITH MULTIPLE SCLEROSIS

Abstract

Abstract INTRODUCTION Patients with multiple sclerosis (MS) may be at higher risk of brain tumors (Khalil 2012, London 2020, etc.). However, MS patients have been reported to have adverse effects from radiotherapy, a mainstay of CNS treatment. In the last ten years, radiation techniques have improved. We submit a case report of an MS patient with demyelinating CNS lesions shortly after radiation therapy for an astrocytoma and review the literature. Case description: A 40-year-old woman with a history of MS treated with Siponimod underwent resection of a right frontotemporal grade 2 astrocytoma, IDH mutant. She received adjuvant proton radiotherapy (54 Gy(RBE) over 30 fractions) followed by temozolomide chemotherapy. She tolerated radiotherapy well and only experienced grade 1 dermatitis, fatigue, and hair loss within the field of treatment. 1-month post radiation MRI was stable. 4 months post radiation there was an asymptomatic new typical demyelinating lesion on FLAIR without T1 or contrast changes. This was outside the high dose radiation field (i.e. received ~30 Gy(RBE)). Her Siponimod had been held for concerns of interactions with radiation or chemotherapy. DISCUSSION Cases have been reported of people with MS experiencing adverse effects from radiotherapy. Murphy, et al., reported a 30-year-old woman with MS experiencing an attack of demyelination 2 months after radiotherapy (50 Gy over 25 fractions), and Borges, et al. presents a 28-year-old patient who experienced radiotherapy-induced inflammatory demyelination after receiving whole-ventricular irradiation (24 Gy over 15 fractions). Miller, et al., reported 6 patients without exacerbations of MS but had developed grade 4 neurotoxicity in a median of 1 year; most of those patients were treated with older radiation techniques, however. Radiotherapy effects in people with MS is a topic that should be revisited in the era of more conformal RT techniques, effective MS therapies, and cancer treatment including immunotherapy.