In GBM, MPM and Non-Small Cell Lung Cancer (NSCLC) TTFields alter DNA repair through downregulation of BRCA1 (BReast CAncer gene 1) pathway genes and alteration of homologous recombination (HR) causing chromatid aberrations, DNA fragmentation and mitotic catastrophe [10, 15, 66]. The gene discussed is BRCA1; the disease is glioblastoma.