A transmissible cancer that arose in a marine mussel spread from a single animal to become a global pathogen affecting two other mussel species in both Europe and South America.

Tumoral group phenotypic compositions and their relationships with the fitness of individual malignant cells in different ecological contexts represent crucial, previously unexplored dynamics in tumor progression.

Genome sequencing analysis dissects the origins and evolution of cancer transmission between clam species in the Seas of Southern Europe.