gms | German Medical Science

Background: Stereotactic radiosurgery (SRS) is a non-invasive treatment alternative for small brain metastases as effective as microsurgery. In principle, SRS represents the application of a high radiation dose with a steep dose fall-off for protection of normal brain tissue.

Methods and Results: Volumes of up to 3cc may be treated very efficiently by SRS using a single dose of 18-20Gy. With a median survival time of 9-10 months SRS resulted in local tumor control rates of 90-97%% (Huang et al., 1999 und Levine et al., 1999). Larger metastases (>3cc) may benefit from fractionated SRS (fSRS) using treatment schedules of 5x7Gy (Ernst-Stecken et al., 2006) or microsurgery. Figure 1 [Fig. 1] gives results of the treatment of a patient with intracerebral metastases from breast cancer following fSRS. It is noteworthy that brain metastases from primaries obviously regarded as “radioresistant” like renal cell carcinoma and melanoma may specifically benefit from this fSRS-approach. Tumor control and survival rates do not differ from results following SRS for singular metastases. Adjuvant whole brain irradiation (WBI) following microsurgery or SRS of a solitary brain metastasis significantly reduced local as well as diffuse intracerebral recurrence (70% for microsurgery alone vs. 18% after microsurgery and WBI, Patchell et al., 1998). In addition, RTOG study 9805 demonstrated a survival benefit for patients with RPA class I (single metastasis, no extracerebral tumor) with WBI plus SRS as compared to WBI alone. Median survival time increased from 4.9 months to 6.5 months (p=0.04). In addition, patients with 1-3 metastases experienced benefits in terms of prolonged steroid use and neurologic performance status following WBI and SRS a scompared to WBI alone.

Conclusions: Microsurgery and WBI remain the standard treatment for patients with operable single brain metastases. However, for non-operable cases (1-3 metastases) SRS plus WBI resulted in better local tumor control, improved neurological performance and less steroid use compared to WBI alone. A significant survival benefit was demonstrated for patients with single brain metastasis following the combined approach. For patients with larger metastases (>3cc) fSRS is a proven treatment alternative as effective as SRS.

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