“…Since proposed, tree models have been used by many researchers to explore the molecular mechanism of tumor development, including the CGH data from renal cell carcinoma [20,22] , hereditary breast cancers [23] , bladder cancer [24] , head and neck squamous cell cancer [25] , nasopharyngeal carcinoma [14,26] , thymoma [27] , and rat mammary tumors [28] , and breakpoint data from ovarian cancer [21] . These models have been used to identify early events, as well as marker events of subtypes of tumors, defining the sequence of these events and the involved pathways.…”