Cancer is a dynamic process. Rapid mutations form complex tumor genomes. Understanding their differences with normal genomes and their evolution can help predict the evolution of the disease and possible medical interventions. To predict the evolution of cancer cells, El-Kebir et al. established the copy-number tree problem and proved it to be NP-hard. We found that the proof is not exactly correct. Thus, we established the revised copy-number tree problem and transformed the revised maximum parsimony phylogeny problem to the revised copy-number tree problem by a polynomial transformation.