Tumor evolution

Clonal heterogeneity and tumor evolution: past, present, and the future.  Cell 168: 613–628.

"In a famous thought experiment, evolutionary biologist Stephen Jay Gould asked, if the 'tape of life' could be turned back to the very beginning, would the same outcome prevail?  While re-playing the tape of life remains a hypothetical experiment, the 'tape of cancer' is being played and re-played with increasing regularity and too frequently with lethal results."