Histology-Stratified Tumor Control and Patient Survival After Stereotactic Radiosurgery for Pineal Region Tumors: A Report From the International Gamma Knife Research Foundation

BACKGROUND: Pineal region tumors represent a rare and histologically diverse group of lesions. Few studies are available to guide management and the outcomes after stereotactic radiosurgery (SRS). METHODS: Patients who underwent SRS for a pineal region tumor and for whom at least 6 months of imaging follow-up was available were retrospectively assessed in 5 centers. Data were collected from the medical record and histology level analyses were performed, including actuarial tumor control and survival analyses. RESULTS: A total of 70 patients were treated between 1989 and 2014 with a median follow-up of 47 months. Diagnoses were pineocytoma (37%), pineoblastoma (19%), pineal parenchymal tumor of intermediate differentiation (10%), papillary tumor of the pineal region (9%), germinoma (7%), teratoma (3%), embryonal carcinoma (1%), and unknown (14%). Median prescription dose was 15 Gy at the 50% isodose line. Actuarial local control and survival rates were 81% and 76% at 20 years for pineocytoma, 50% and 56% at 5 years for pineal parenchymal tumor of intermediate differentiation, 27% and 48% at 5 years for pineoblastoma, 33% and 100% at 5 years for papillary tumor of the pineal region, 80% and 80% at 20 years for germinoma, and 61% and 67% at 5 years for tumors of unknown histology. New focal neurological deficit, Parinaud syndrome, and hydrocephalus occurred in 9%, 7%, and 3% of cases, respectively. . CONCLUSIONS: SRS is a safe modality for the management of pineal region tumors. Its specific role is highly dependent on tumor histology. As such, all efforts should be made to obtain a reliable histologic diagnosis.