Among several forms of pancreatic cancer, one of them affects specifically women, often young. How is this possible, even though the pancreas is an organ with little exposure to sex hormones? This pancreatic cancer, known as “mucinous cyst”, has strange similarities with another mucinous cancer, affecting the ovaries. By conducting large-scale analyses of genomic data, researchers at the University of Geneva (UNIGE) and at the University Hospitals of Geneva (HUG), Switzerland, in collaboration with colleagues from the United States have provided an answer: both tumours originate from embryonic germ cells. While still undifferentiated, these cells migrate to the reproductive organs. On their way, some can mistakenly stop in other organs, bringing a risk of tumour that may occur 30 years later. By allowing a better classification of these mucinous tumours, this study, to be read in the Journal of Pathology, paves the way for a more appropriate and personalized management aligned with the tumour’s origin.