10170-NT-3 Continuous treatment of Novo-TTF over 4 years revealed prolonged survival effect and the best practice for skin care

Abstract Background Novo-TTF (Optune) has been covered by insurance in Japan for newly diagnosed glioblastoma (GBM) since 2018 and is currently recognized as a standard therapy. However, reports on its long-term use are limited, partly due to the short median survival of GBM. We report a case of continuous Optune use for over 4 years, focusing on efficacy and adverse events. Case A 68-year-old right-handed self-employed man presented with left homonymous hemianopia. Imaging revealed a hemorrhagic lesion in the right occipital subcortex. Two months later, contrast-enhanced MRI demonstrated ring enhancement, and craniotomy was performed. Gross total resection was achieved, and histopathology confirmed glioblastoma, IDH-wildtype, CNS-WHO grade 4, with MGMT promoter methylation and TERT promoter mutation. Postoperatively, Stupp regimen chemoradiotherapy was administered, and Optune was initiated approximately 3 months after surgery. The device usage rate ranged from 85% to 95% (median 91%) over 4 years. The patient maintained a Karnofsky Performance Status of 90, discontinued maintenance chemotherapy at 15 months, and remained recurrence-free at 54 months post-surgery. Scalp dermatitis began during radiotherapy and continued after Optune initiation, managed with topical treatments. Skin symptoms fluctuated with a tendency to worsen in summer and improve in autumn but remained manageable. No other significant adverse events were observed. Discussion In this case, multimodal therapy combined with Optune achieved more than four years of progression-free survival. While the skin lesions did not pose a major obstacle to the continuation of Optune therapy, ongoing dermatological management was required. To the best of our knowledge, there have been no previous reports describing long-term Optune use with detailed observations of skin complications and their management, making this case a valuable clinical experience.