10119-ACT-9 LONG-TERM USAGE OF TUMOR-TREATING FIELDS THERAPY FOR TREATMENT OF MALIGNANT GLIOMA

Abstract OBJECTIVE Tumor-Treating Fields therapy has been the standard therapy for newly diagnosed glioblastoma since 2018 in Japan. The patients are recommended to use the system for 18 or more hours per day. In practice, some patients could not use it long-term and dropped out from this therapy. We examined factors related to interruption of NovoTTF use. METHODS We reviewed the clinical course of NovoTTF-100A system (NovoTTF) in cases at our hospital from April 2018 to May 2023. We compared the group that continued to use NovoTTF or used it until the disease progressed (Group A) with the group that discontinued it for their own reasons (Group B). RESULTS There were 22 patients, 14 in group A and 8 in group B. The mean preoperative tumor volume was 25.3 cm3 in group A and 38.7 cm3 in group B (p=0.27). The mean number of days of NovoTTF use was 437 in Group A and 27 in Group B (p<0.05). The mean usage rate was 70% in group A and 22% in group B (p<0.05). Tumors were located in 6 frontal lobes, 3 temporal lobes, 3 parietal lobes, 1 basal ganglia, and 1 thalamus in group A, while 1 frontal lobe, 6 temporal lobes, and 1 parietal lobe in group B. Among six temporal lobe cases in group B, five revealed temporal lesions in the dominant hemisphere, causing moderate or severe aphasia before surgery. CONCLUSION The group that continued NovoTTF maintained its usage rate as well as the number of days of use, while the group of cases that discontinued for their own reasons had a low use rate. Five of the eight discontinued cases had temporal lobe lesions in the dominant hemisphere and had aphasia symptoms. Difficulties in understanding the need for NovoTTF may have contributed to the discontinuation.