Paper the story is based on: https://www.cell.com/cell/fulltext/S0092-8674(26)00278-3
This ecDNA sounds a lot like the tactics of viruses & prokaryotes, and supports my mental model of cancer as a sort of virtual organism within us, with a strategy of defecting from multicellularity. I imagine this niche has been fought with since the beginning of cells getting together, and cancer today represents billions of years of selection for that strategy.