P14.38 Clinical experience with tumor treating fields (TTFields) treatment for posterior fossa tumors

Abstract

Abstract Introduction: TTFields brought a new concept in the treatment of brain tumors. It was tested and recommended for use in supra-tentorial lesions. There is a paucity of data available about TTFields safety and efficacy for infra-tentorial lesion. Method: Patients with posterior fossa tumors were treated with the Optune® system. Initial transducer array positioning and all technical characteristic were performed with technical support from Novocure. Results: Two patients with posterior fossa glial tumors were treated. The first is a 27 years old male with DIPG (without pathological confirmation of the tumor grade) who was treated with Stupp protocol. Treatment with TTFields commenced with TMZ adjuvant phase. The second patient is a 33 years old female with cerebello-pontine astrocytoma WHO grade III, IDH I mutated. This patient was treated with partial resection and Stupp protocol. TTFields treatment was started after completing 12 TMZ adjuvant cycles with measurable stable disease. Duration and compliance of TTFields treatment for first patient is 286 days and 86% and for second patient is 168 days and 93.6%. The skin toxicity is minimal and did not require treatment interruption. There is no other TTFields related toxicity. The MRI evaluation had showed improvement in the first patient and stable disease in the second. Conclusion: According to our knowledge, this is the first report of clinical experience with TTFields treatment for posterior fossa tumors. In our experience, the treatment is feasible and with equal toxicity to previously reported supra-tentorial lesions. Small patient population and short follow up do not allow efficacy evaluation.