A RADIATION ONCOLOGIST’S EXPERIENCE TREATING MALIGNANT GLIOMA WITH TUMOR TREATING FIELDS IN CANADA

The FDA approved tumor treating fields (TTFields) in 2011. Through Health Canada special access, a limited number of treatments were provided prior to regulatory approval. This work describes a single physician’s experience with TTFields. With ethics approval, charts were retrospectively reviewed. Access provided as an extension of prior research was excluded. Kaplan-Meier estimates were used for survival and time on treatment. From 2013-2022, 62 cases were identified. 65% from Quebec, 21% from Ontario and the rest from either Alberta or British Colombia. TTFields were prescribed as an adjuvant following chemo-radiation in 41 cases and for recurrent disease in 21. Median age was 49 (range 16-75). 76% of patients were male. Median KPS was 75%. 95% of tumors were classified as glioblastoma by the criteria used at the time of diagnosis (IDH positive in 4). Where known, 40% had MGMT promoter methylation. Adjuvant treatment started a median of 1.0 months following radiotherapy. Recurrent patients had had a median of 2 prior lines of treatment (range 1-9). Two young adults discontinued treatment after less than one week but otherwise patients tolerated the device until treatment was recommended to be discontinued. Median OS for adjuvant patients was 15.4 months, 5.3 months for recurrent patients. For adjuvant patients, median estimated time on treatment was 7 months. It was possible to offer TTFields over a wide geographic area with support from device specialists. Treatment may be more easily integrated into care with the development of a larger network of prescribers.