Stereotactic gamma radiosurgery for pineal and related tumors.

The role of gamma knife radiosurgery as an additional therapy after conventional treatments for pineal and related tumors was studied in 30 of 33 tumors with a mean follow-up of 23.3 months. Overall results showed that a complete response was obtained in 8 cases (26.7%) and the response rate was 73.3%. However, tumor progression was found in 8 cases (26.7%), of whom 7 (23.3%) died as a consequence. Germinoma and pineocytoma showed higher response and control rates (100%), and neither progression nor death occurred after gamma knife treatment. Germinoma with syncytiotrophoblastic giant cells (STGC) has been thought to have an intermediate prognosis. Two of our cases showed a partial response and another progression. Malignant germ cell tumor and pineoblastoma showed unfavorable responses and prognosis, with the response and progression rates both being 50%. Gamma knife radiosurgery was the initial treatment in three pineal tumor cases without a histological diagnosis, and one complete and two partial responses were obtained. Gamma knife radiosurgery is expected to be an effective and novel approach to pineal and related tumors, not only as an adjuvant but also as an initial treatment.