Introduction: Brain metastases (BrM) of several cancers are common (for example, lung, breast, renal, melanoma). Conversely, there is little information in the literature regarding treatment modalities and outcomes for BrM from cancers that infrequently metastasize to the brain. We evaluate the role of stereotactic radiosurgery (SRS) to treat BrM from atypical primary histologies.
Methods: We reviewed the Cleveland Clinic brain tumor database for atypical brain metastases over fifteen years, from March 1997 to October 2012. Patient data was collected from electronic medical records. Univariate and multivariate statistical analysis were completed with IBM-SPSS 19 software.
Results: We identified 179 patients with atypical pathologies [total of 364 tumors], out of >1,600 BrM patients treated with SRS. There were 95 men (53%); median age was 61 years. Ninety-three patients had single lesions (52%); the patients with multiple had a range of 2-8 tumors. Nineteen different primary tumor pathologies were represented. Median overall survival (mOS) was calculated for the entire cohort (7.9 months) and for each individual group by pathology (ranging from 3.2 to 13.5 months between the worst and best groups respectively). The cohort was divided into two prognostic groups (PGs) based on mOS survival, of better or worse than 7 months. The better PG consisted of small bowel, endometrial, gastric, germ cell, liver, ovarian, parotid, prostate, sinus cavity, thymoma, thyroid and urothelial cancers (mOS 12.1 months) while the worse PG contained colorectal, esophageal, mesothelioma, oral cavity, pancreatic, sarcomas and unknown primary cancers (mOS 6.3 months). On multivariate analyses, both PG (p<0.0001) and GPA group (p=0.003) were independent, significant prognostic factors for mOS.
Conclusions: SRS is one reasonable treatment option for patients with CNS metastases even if they are from atypical primary tumor types. Separating patients by primary tumor histology and GPA group may help to guide expectations for OS after SRS.
Patient Care: Brain metastases are a common condition treated with stereotactic radiosurgery. While the efficacy of SRS is established for tumor types that are common (breast, lung, renal, melanoma) it is not widely reported for metastases from other atypical histologies. These patients with rare brain metastases may be further characterized to help guide treatment decisions and prognosis for overall survival.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Identify tumor types that rarely metastasize to the brain.
2) Evaluate the relative efficacy of stereotactic radiosurgery as it relates to these rare brain metastases.
3) Describe prognostic factors that may affect overall survival in patients with metastatic brain tumors.