Botulinum Toxin as Prophylaxis for Adverse Dermatologic Effects of Tumor-Treatment Fields (TTF) (P6.132)

Objective: Glioblastoma therapy traditionally consists of maximal surgical debulking and radiation therapy with concomitant chemotherapy. TTFields were FDA-approved for recurrent glioblastoma in 2011. Transducer arrays are placed on a shaved scalp and a conductive hydrogrel forms the contact. The transducers emit low intensity (1–2 V/cm), intermediate frequency (200 Hz) wavelengths which interfere with mitotic microtubular assembly in rapidly dividing cancer cells, leading to apoptosis. The TTFields must be worn for at least 18 hours/day for optimal results. Skin irritation is the most common adverse effect associated with this device treatment. Background: 57 year-old left-handed woman presented with progressive left face and hand numbness persisting over one day. Brain MRI demonstrated two ring-enhancing lesions in the right precentral gyrus. The patient underwent a frontal craniotomy near-total resection. Pathology indicated glioblastoma (MGMT methylated, IDH1 negative). She underwent radiotherapy (6000 cGy in 30 fx) with concurrent temozolomide followed by 5 cycles of post-radiation chemotherapy. Two months later, in the setting of tumor progression, she elected to pursue TTFields. Treatment onset was during warm summer months and was complicated by contact dermatitis, folliculitis, erosions, and ulcerations at the sites of contact with hydrogel. It was hypothesized that perspiration caused these complications because they abated during the winter. Eleven months into TTFields therapy, she began intradermal botulinum toxin injections of the scalp and forehead every 3–4 months. Her hyperhidrosis and tolerance of TTFields improved significantly. She remains on TTFields 22 months after beginning treatment. Design/Methods: NA Results: NA Conclusions: TTFields has been shown to prolong progression-free and overall survival in patients with glioblastoma when used as an adjunct to surgery, radiotherapy, and chemotherapy, but compliance is critical for efficacy. Botulinum toxin therapy reduced dermatologic adverse effects, and enabled compliance in this patient. A systematic investigation of this remedy should be considered to improve patient comfort and quality of life. Disclosure: Dr. Bucklan has nothing to disclose. Dr. Stevens has nothing to disclose. Dr. Peereboom has nothing to disclose. Dr. Vidimos has nothing to disclose. Dr. Staugaitis has nothing to disclose.