Why do alterations of certain genes cause cancer only in specific organs of the human body? Scientists at the German Cancer Consortium (DKTK), the Technical University of Munich (TUM), and the University Medical Center Göttingen have now demonstrated that cells originating from different organs are differentially susceptible to activating mutations in cancer drivers: The same mutation in precursor cells of the pancreas or the bile duct leads to fundamental different outcomes. The team discovered for the first time that tissue specific genetic interactions are responsible for the differential susceptibility of the biliary and the pancreatic epithelium towards transformation by oncogenes. The new findings could guide more precise therapeutic decision making in the future.