Jonathan Ledermann, MD, FRCP from University College Hospital, London, UK discusses the advancement of poly ADP ribose polymerase (PARP) inhibitor treatment in prostate, gastric and pancreatic cancer at the 2016 annual meeting of the European Society of Medical Oncology (ESMO), held in Copenhagen, Denmark. Prof. Ledermann begins by describing a subset of prostate cancer patients who have a common defect in PARP inhibitor activity, homologous recombination, in which there is an inability to repair double stranded DNA breaks correctly. PARP inhibitor treatment has shown promise in small studies and larger studies in the future will provide more insight into this treatment option. Prof. Ledermann continues to discuss ongoing trials into the use of PARP inhibitors in gastric and pancreatic cancer, providing the example of olaparib being tested in pancreatic patients with BRCA mutations.