By contrast, tumor progression trees make it possible to identify the events occurring at the start of tumorigenesis, even from a set of very complex samples, as in patient P3, in which a subset of ten early aberrations was identified, including two amplicons reported to be frequent in bladder cancer [21-25], at 11q13.3 (Cyclin D1) and 8q22.2 (no known oncogene). Here, CCND1 is linked to urinary bladder cancer.