[Hypofractionated stereotactic irradiation for optic nerve glioma]

Optic nerve glioma is a rather rare tumor. It predominantly arises in pediatric patients, including those with type I neurofibromatosis. This neoplasm is accompanied by decreased visual function and exophthalmos. Treatment strategy is individualized depending on age, volume and spread of tumor, as well as severity of clinical manifestations. Possible treatment options are surgical resection, chemotherapy, radiotherapy and their combination. Radiotherapy can be recommended for patients with intact visual functions, no severe proptosis and trophic lesions. Classic fractionation mode is used as a standard. Currently, the possibility of hypofractionated irradiation is being considered.

To evaluate safety and efficacy of hypofractionated radiotherapy in patients with optic nerve glioma.

Sixteen patients with optic nerve gliomas underwent hypofractionated stereotactic irradiation (CyberKnife) between May 2014 and October 2019. Single focal dose was 5.5 Gy. There were 5 fractions up to total focal dose of 27.5 Gy. The sample enrolled 14 children with a median age of 4 years (range 23 months - 13 years) and 2 adults aged 47 and 66 years, respectively. Median of tumor volume was 2.77 cm³ (range 1.69-10.01 cm³).

Tumor growth control was achieved in all patients, partial remission was observed in 5 (32%) patients. None patient had deterioration of visual function. Improvement of visual acuity was noted in 3 (19%) cases. Visual field enlargement occurred in 4 (67%) out of 6 patients who were preoperatively examined. After irradiation, proptosis decreased by ≥ 1 mm in 9 (60%) out of 15 patients.