PARP1 and cancer: We hypothesize that, when translated to the clinic, PET imaging with radiolabeled compounds such as 18F-olaparib will allow better patient selection by determining tumor drug uptake; measurement of the biologic effects of genotoxic cancer treatment, such as chemo- and radiotherapy; and better patient stratification, making the therapeutic use of PARP inhibitors even more effective, albeit in a more stringently selected patient population.