Radiosurgical treatment of patients with intracranial pilocytic astrocytomas

The study objective is to assess the outcomes after stereotactic radiosurgical treatment (SRS) in patients with pilocytic astrocytomas after non-radical surgery and after continued tumor growth.

Materials and methods. The report includes 56 patients (37 males and 19 females) who have undergone SRS in N. N. Burdenko National Medical Research Center of Neurosurgery from March 2005 to January 2018.

Results. The majority of patients (75 %) were children. Almost 43 % of patients underwent SRS as part of the primary treatment after biopsy or incomplete removal, other patients – in the event of continued tumor growth after non-total surgery. Tumors involved the cerebellum (41 %), brainstem (23 %), thalamus (19.6 %) and cerebral hemispheres (16.1 %). The median tumor volume was 1.9 cm3 (0.14–19.00 cm3), 23 % of patients had cysts in the tumor. The prescribed dose was 12 to 22 Gy (median 18 Gy) over 50–80 % isodose line. The follow-up was available for 54 (96.4 %) patients. The median follow-up was 67 months (3–151 months). All patients were alive at the end of the follow-up examination. In 14 (25 %) patients, the development of pseudo-progression (PSP) was noted. The median detection of PSP is 11 months (3–65 months). Of these, in 7 (50 %) patients PSP was accompanied by clinical deterioration: in 5 – an increase in general cerebral symptoms and in 1 patient – an episode and an increase in cerebellar symptoms. Eight (57 %) patients with PSP were reoperated: 4 underwent removal of the tumor, 4 – emptying of the cyst and placement of the Ommaya reservoir, which led to regression of the existing symptoms. No other toxicity was observed in patients. At the time of the completion of the follow-up examination (with a given median follow-up), no relapses were detected. There was no clinical deterioration after SRS.

Conclusion. Radiosurgical treatment is an effective and safe method of radiation treatment for patients with primary pilocytic astrocytomas and recurrent pilocytic astrocytomas, providing control over tumor growth in all patients with a low risk of complications.

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