Background: The prognosis of metastatic melanomas to the brain (MBM) is variable with prolonged survival in a subset. It is unclear whether MBM differ from extracranial metastases (EcM) and primary melanomas (PrM).
Methods: To study the biology of MBM, histopathologic analysis of tumor blocks from patients' craniotomy samples and whole-genome expression profiling (WGEP) with confirmatory immunohistochemistry were performed.
Results: High mononuclear infiltrate and low intratumoral hemorrhage were associated with prolonged overall survival (OS). Pathway analysis of WGEP data from 29 such craniotomy tumor blocks demonstrated that several immune-related BioCarta gene sets were associated with prolonged OS. WGEP analysis of MBM in comparison with same-patient EcM and PrM showed that MBM and EcM were similar, but both differ significantly from PrM. Immunohistochemical analysis revealed that peritumoral CD3⁺ and CD8⁺ cells were associated with prolonged OS.
Conclusions: MBMs are more similar to EcM compared with PrM. Immune infiltrate is a favorable prognostic factor for MBM.
Keywords: brain metastases; craniotomy immune infiltrate; gene expression profiling; melanoma.
© 2013 American Cancer Society.