Stereotactic radiosurgery in the treatment of brain metastases from gastrointestinal primaries.

Brain metastases from gastrointestinal (GI) primary malignancies are generally less common than those arising from other primary locations. Our purpose was to analyze the efficacy of stereotactic radiosurgery (SRS) in the treatment of patients with brain metastases from GI malignancies in the modern radiosurgical and systemic therapy era. A review of patients treated with SRS to brain metastases from GI primaries treated from 1996 to 2015 at our institution was conducted. Clinical, therapeutic, dosimetric and radiographic characteristics were collected and analyzed for an association with brain tumor local control (LC) and overall survival (OS) following SRS using univariate and multivariate (MVA) analyses. 261 brain metastases were identified from 86 patients meeting inclusion criteria. The most common primary location was rectum (n = 36). LC was 94.1 % at last follow up and margin dose ≥20 Gy was associated with improved LC on MVA (p = 0.038). Median OS was 6.2 months and was improved with higher performance score and luminal primary location on MVA (p = 0.002 and 0.015, respectively). Tumor histology, whole brain irradiation, targeted therapies, and antineoplastic therapies were not associated with improved LC or OS on MVA. SRS provides favorable LC of brain metastases of GI origin, and margin doses of at least 20 Gy should be considered when clinically appropriate. Compared to non-luminal primaries, patients with brain metastases from a luminal primary demonstrate improved OS.