How do cells become cancerous, multiply uncontrollably, and form into tumors? And what role do aberrant embryonic stem cells play? These are big questions explored by medical researchers since the embryonic theory of cancer was first proposed in the 19th century. Now, in an exciting new study adding to the global pool of knowledge about the roots of human cancers, researchers are establishing a clear link between different types of cancers and their embryonic origins. They also identify new concepts that can be considered in future drug discovery projects and used in standard chemotherapeutics in the clinic.