  This manuscript has been written to address questions related to our recent
publication (Science 347:78-81, 2015). We appreciate the many reactions to this
paper that have been communicated to us, either privately or publicly. The
following addresses several of the most important statistical and technical
issues related to our analysis and conclusions. Our responses to non-technical
questions are available at
http://www.hopkinsmedicine.org/news/media/releases/bad_luck_of_random_mutations_plays_predominant_role_in_cancer_study_shows
