On the basis of the interaction of ERG and other ETS fusions with the DNA repair proteins PARP1 and DNA-PKc, use of PARP inhibitors has shown initial promise and is being tested in ETS fusion-positive prostate cancers [reviewed in Kumar-Sinha et al. (2015) and Pederzoli et al. (2020)]. This evidence concerns the gene ERG and Familial prostate cancer.