Аннотация:Pilocytic astrocytoma (PA) is a low-grade glial tumor that accounts for 25–30% of all central nervous system (CNS) tumors in children and 2–5% in adult patients [1, 2]. Surgical removal of the tumor is the main treatment for newly diagnosed and relapsing PA [3–5]. In the case of radical surgery, 5-year progression-free survival (PFS) ranges 90–100%. With incomplete removal of the tumor, however, 10-year PFS does not exceed 15–50% with a high risk of recurrence in the first 2–3 years after surgery [3]. After total removal of the tumor, dynamic observation is performed; with incomplete removal, adjuvant treatment is required. Chemotherapy (ChT) is the treatment of choice in newborn children with anterior optic gliomas, which may delay or replace radiation treatment in some patients [6, 7]. An increased risk of developing late toxicity (endocrine and neurocognitive disorders) in younger patients with tumors located in the chiasm-sellar region is the main reason to postpone radiation treatment at a later date, until the onset of progression of the disease [7–9]. Relapse-free survival rates with chemotherapy alone are on average two times lower than after radiation treatment (40–45% versus 75–90%) [6, 7, 9–15]. Radiation therapy has been the standard of care for patients with low grade glioma (PA) for many years and can achieve high survival rates comparable to those of radical tumor resection [9, 13, 15].