Stereotactic radiosurgery for a single brain metastasis: factors impacting control.

OBJECT

Stereotactic radiosurgery (SRS) is well established in the treatment of brain metastases, however it's exact role remains unclear. A single metastasis at presentation raises additional challenges, however there is minimal outcome data within this subgroup. We sought to evaluate the outcomes of treatment in patients with a single brain metastasis, as well as factors impacting local control.

METHODS

All patients treated with SRS for a single brain metastasis were evaluated. Data was collected regarding patient demographics, treatment characteristics, and treatment outcomes. Univariate analyses were performed to evaluate the impact of treatment and patient variables on these outcomes. Emphasis was placed on analyses of factors impacting LC.

RESULTS

Between 1998 and 2011, a total of 141 patients underwent SRS for a single brain metastasis; in addition 31 had surgical resection, 15 received whole brain radiotherapy (WBRT), and 2 underwent both. There was no statistical impact on local control (LC) or distant intracranial control (DIC) with the addition of WBRT or surgery (LC 74%, 100%, and 58%, and DIC 37%, 67%, and 49% for SRS alone, SRS + WBRT, and SRS + surgery, respectively, smallest p = 0.17). Local control was decreased with larger tumors, doses <20Gy, and tight overtreatment ratios (i.e. conformity) (largest p = 0.02), although the independence of these factors could not be established. Long term freedom from requiring future whole brain radiotherapy was 73%.

CONCLUSIONS

SRS alone for patients with single brain metastases demonstrates acceptable intracranial outcomes. Further evaluation into factors impacting LC are warranted.