Article
Stereotactic radiotherapy (SRT) in the treatment of tumors compressing the optic chiasm
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Published: | April 28, 2011 |
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Objective: Microsurgical resection is the treatment of choice for tumors threatening the optic chiasm. However, the risk of post-operative optical impairment of sight is high and therefore the complete removal of the tumor is not always possible. To overcome this difficulty, the efficiency and side-effects of stereotactic radiotherapy (SRT) as a supplemental treatment are analysed.
Methods: Between 2000 and 2009, 266 patients with tumors touching or compressing the chiasm were treated with SRT. 151 of these (57%) were meningiomas, 92 (35%) pituitary adenomas, 15 craniopharyngiomas and 8 brain metastases. The pituitary adenomas and craniopharyngiomas were almost always relapses and progressive residual tumors after 1 – 3 microsurgical resections. In contrast, 62% of the meningiomas received SRT as the primary treatment. All of the benign tumors in close vincinity to the chiasm were treated with SRT in standard fractionation of 1.8 – 2 Gy single-dose up to a 54 or 56 Gy total dose. Hyperfractionated SRT in single doses of 4 Gy was selected for the 8 patients with brain metastases.
Results: Clinically relevant side-effects occurred in 4.4% of all cases, but without additional neurological deficits. No recurrences have been observed in the 92 patients with pituitary adenomas (100% tumor control, 53% tumor shrinkage, 3.6% one-sided visual impairment). After 4 to 8 years, 5 of the 151 meningiomas (3.3%) showed recurrent tumor growth and underwent another surgical intervention and SRT (96.7% tumor control, 54% tumor shrinkage, 2% impairment of sight). For craniopharyngiomas, the corresponding results were 93% tumor control, 73% tumor shrinkage, no optical impairment. The patients with brain metastases died after 7 to 26 months as a result of the metastatic primary tumor.
Conclusions: SRT offers an additional and/or alternative treament option with great efficiency and few side-effects, even for tumors compressing the optic chiasm. The stereotactic fractionation with 1.8 Gy single dose is decisive in order to minimize the risk of neural damage.