Gamma knife therapy for intraocular melanomas

Gamma knife radiosurgery developed by Lars Leksell for the treatment of brain tumors is useful for the treatment of uveal melanomas due to its unique physical features. It allows the delivery of a high single dose with minimum involvement of the surrounding tissue. Encouraged by first positive results by Chinela, Zambrano and Bunge we adopted the procedure for the treatment of uveal melanomas. A multi centric trial in accordance with gamma knife procedure is performed in 4 steps: 1. Fixation of the globe with a retrobulbar anaesthetic block. 2. Stereotactic location of the tumor by CT. 3. Calculation of the isodoses. 4. Radiosurgical procedure. Between June 1992 and February 1993 we treated 6 uveal melanomas with the Leksell gamma knife together with the Department of Neurosurgery and the Institute of Radiotherapy. In 5 out of 6 cases gamma knife therapy could stop further tumor growth. In one case of a juxtapapillary melanoma a reduction of tumor height from 8 to 4 mm could be achieved: early side effects like serous retinal detachment resolving spontaneously after 4 months and hemorrhage at the base of the tumor were remarkable in this patient. According to our first encouraging results treatment with the Leksell Gamma Knife seems to be an alternative therapeutic modality in larger tumors or those located at the posterior pole but definite conclusions about the efficiency of this new therapeutic procedure can only be drawn once. A larger number of patients will have been observed after a longer follow up period. (author)