Evaluation Summary:
Cancers have frequently been found to show little evidence for purifying selection in their patterns of mutations. The key observation here is that tumors with low mutation burden show compelling evidence of efficient selection, but that tumors with high mutation burden do not. This is an important finding. The broader implication is that high mutation load tumors carry a substantial deleterious mutation load and may use common strategies to tolerate them, possibly providing a therapeutic target. Overall this work makes important observational and conceptual contributions to cancer genomics.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #3 agreed to share their name with the authors.)