PIK3CA and cancer: One study showed that brain metastases from multiple cancer types can feature mutations in key oncogenic signaling pathways, including in cell cycle regulators and the PI3K-AKT pathway, that are not easily detected in primary tumors.17 Another recent study revealed unique genetic variants that are exclusive in the MBMs but are absent in the corresponding extracranial metastases.18 However, currently available data has failed to find significant enrichment of private mutations in a specific gene or genes in MBMs.16,19