Stereotactic Radiosurgery for Pineal and Related Tumors

Abstract

Radiosurgery is increasingly being used to treat pineal region tumors, either as an additional therapy after conventional treatments or as a primary treatment. We report our experience with Gamma Knife radiosurgery (GKRS) for the treatment of pineal and related tumors. Forty-nine patients underwent GKRS for pineal and related tumors (n = 74) between February 1992 and September 2007. The diagnosis was germ cell tumors (GCTs) in 38 patients (53 tumors), pineal parenchymal tumors (PPTs) in 9 (19 tumors), and unknown in 2 (2 tumors). The mean treatment volume was 3.3 ml (range 0.1-22 ml) in GCT cases and 3.7 ml (range 0.3-23 ml) in PPT cases. Prescribed doses around 50% isodose line ranged from 9.9 to 25.7 Gy. One patient (one tumor) with pineocytoma was lost to follow-up. Median clinical and imaging follow-up in the remaining 48 cases was 33.5 months (range, 3-192 months). Survival rates at 5 years and 10 years after GKRS in GCT cases (n = 38) were both 68%. They were 100 and 67%, respectively, in PPT cases (n = 8). We evaluated the treatment results with categorization of GCT cases into 2 groups, i.e. germinoma (group 1), and germinoma with syncytiotrophoblastic giant cell and malignant GCT (group 2). PPT cases were also divided into 2 groups, i.e. pineocytoma (group 3) and pineoblastoma and mixed pineocytoma/pineoblastoma (group 4). Local tumor control (LTC) rates at 3 and 5 years were 82% in group 1 (n = 18), 72 and 62% in group 2 (n = 35), and 85% in group 3 (n = 13). LTC rate at 2 years was 30% in group 4 (n = 5). In group 1 (n = 16), progression-free survival (PFS) rates at 3 and 5 years were 79 and 63%. They were 43 and 37% in group 2 (n = 22), and 80% in group 3 (n = 5). PFS rate at 2 years was 33% in group 4 (n = 3). Germinoma and pineocytoma showed higher LTC and PFS rates after GKRS, though pineoblastoma was liable to relapse. Intermediate prognosis was obtained in germinoma with syncytiotrophoblastic giant cell and malignant GCT. GKRS is expected to be an effective and safe adjuvant treatment approach to pineal and related tumors.