AB011. A propensity-score matched prospective study on the impact of tumour treating fields (TTF) on overall survival and quality of life in newly diagnosed WHO grade 4 astrocytoma patients.

Background: World Health Organization (WHO) grade 4 astrocytoma is a high-grade brain tumour in adults. Tumour treating fields (TTF) has been shown to improve overall survival (OS). Few studies have explored quality-of-life (QoL) in these patients. This study aims to assess the QoL of TTF patients and OS.

Methods: This was a prospective multicenter study of adult patients diagnosed with WHO grade 4 astrocytoma from 2018 to 2023 receiving TTF for >1 month after completing standard therapy. A propensity-score matched comparison with a 1:2 ratio with historical control was performed for OS analysis. The patients completed European Organisation for Research and Treatment of Cancer (EORTC) QLQ-30/BN20 questionnaires before TTF and at 3-month interval. Primary outcomes included OS, and secondary outcomes included QoL and TTF-associated adverse effects at 3 months.

Results: A total of 141 patients were reviewed, with TTF patients (n=47, 33%) and propensity-score matched controls (n=94). The mean duration of TTF use was 10±8 months. The mean age of the TTF group was 54±13 years, and for the control group 52±13 years. Sixty percent (n=28) were male, similar to the control group with 71% (n=67) (P=0.16). Seventy-two percent of TTF patients had preoperative Karnofsky Performance Scale (KPS) score ≥80, while controls had 70% (P=0.79). Five (11%) TTF patients and 8 (9%) controls were IDH1 mutant (P=0.70). Twenty (43%) TTF patients and 42 (45%) controls were O6-methylguanine-DNA methyltransferase promoter (pMGMT) methylated (P=0.81). Twenty-one (45%) of TTF patients and 55 (59%) of controls had gross total resection (P=0.72). After adjusting for independent predictors for OS, the median OS of the TTF group was 22.4 months [interquartile range (IQR): 18.6-26.5 months], significantly longer than the control group (17.2 months; IQR: 12.1-22.3 months) (log-rank test: P=0.01). Forty-seven TTF patients and 40 control patients completed EORTC questionnaires. There was no difference for EORTC functional and symptom scores between the TTF and control group [P=0.45, analysis of variance (ANOVA)] at 3 months. Thirty-two (67%) of TTF patients reported associated RTOG grade I scalp dermatitis.

Conclusions: TTF for WHO grade 4 astrocytoma patients is an independent predictor for OS. QoL between the groups was similar, and overall QoL over time for TTF patients was not affected. TTF is a novel and effective outpatient treatment with minimal adverse effects.