Bialy Replies to a comment from

In the words of one scientist who read these pages in manuscript, “It might appear, especially to people who read books with references,” as though I “have given short shrift to exciting new developments in clinical oncology with drugs such as Gleevec” and to “a large literature that shows specific mutations in genes like rb, p53 and BRCA1 and BRCA2 generate polyclonal tumors and are sufficient for cancer.” For those readers, I offer the following by way of explanation.