Brain Metastases Have Different Genetic Mutations Than the Primary Tumor; Many May Be Targetable with Existing Chemotherapy; International Study Suggests Routinely Looking for These Mutations May Benefit Patients

The development of brain metastases is a devastating complication of cancer, leading to the death of more than half of patients whose cancer spreads to the brain. A new study finds that, while brain metastases share some genetic characteristics with the primary tumors from which they originated, they also carry unique genetic mutations, indicating that the evolutionary pathways of the metastatic and the primary tumors have diverged, which may change sensitivities to targeted therapy drugs. The report from an international collaboration was published online on September 26, 2015 in Cancer Discovery to coincide with a presentation at the European Cancer Congress and European Society for Medical Oncology meeting in Vienna, Austria. "Our study demonstrates that, while brain metastases and primary tumors share a common ancestry, they continue to evolve separately," says Priscilla Brastianos (photo), M.D., Director of the Brain Metastasis Program at the Massachusetts General Hospital (MGH) Cancer Center, co-lead and co-corresponding author of the Cancer Discovery paper. "This is tremendously important, as we demonstrate that brain metastases may have clinically significant mutations that have not been detected either in the primary tumor biopsy or in metastases from other parts of the body. We also showed that multiple brain metastases from the same patient share nearly all clinically significant mutations." The Cancer Discovery article is titled “Genomic Characterization of Brain Metastases Reveals Branched Evolution and Potential Therapeutic Targets.” Brain metastases commonly develop from melanomas, lung, or breast cancers and can appear despite the primary tumor's being well controlled by drugs that target mutations driving its growth.
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