Propensity-score matched pair comparison of whole brain with simultaneous in-field boost radiotherapy and stereotactic radiosurgery.

Abstract

To compare lesional stereotactic radiosurgery to whole brain (WBRT) radiotherapy with simultaneous in-field boost for brain metastases in terms of overall survival. A retrospective review was performed on two institutional databases of 500 patients diagnosed with brain metastatic disease who received either stereotactic radiosurgery (SRS, n = 381) or whole brain with simultaneous in-field boost radiotherapy (SIB, n = 119), between 2002 and 2011. Propensity-score matching was utilized to obtain two groups with similar known prognostic factor characteristics. Kaplan-Meier and univariable/multivariable Cox modeling were conducted to assess the treatment impact on overall survival (OS). Propensity-score matching created a matched cohort of 178 patients (89 SRS/SIB) with similar baseline characteristics. Multivariable analysis demonstrated that presence/absence of systemic metastases, patient age, tumor volume, and presence/absence of active primary were found to be more predictive of OS than treatment assignment (p = 0.38). SIB was associated with reduced intracranial failure likely due to the WBRT component of the treatment (HR 0.36, p<0.001). Adjusting for other predictive factors, treatment with either SRS or SIB did not result in any statistically significant difference in OS; however, observed intracranial failure was different due to the use of WBRT in the SIB cohort.