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For international communication in cancer, staging systems such as TNM are essential; however, the principles and processes used to decide about changes in every new edition of TNM need to be subject to debate. Changes with major impact for patient treatment are introduced without evidence. We think that TNM should be a continual reactive process, rather than a proactive process. Changes should only occur after extensive discussion within the community, and before the introduction of any changes these should be tested for reproducibility and compared to the currently used gold standard. TNM should not be used to test hypotheses. It should introduce established facts that are beneficial to predicting patient prognosis. TNM should thus be restructured on a basis equivalent to evidence-based guidelines. The strength of the evidence should be explicitly stated and the evidence base given. It is time for the principles of staging to be widely debated and new principles and processes to be introduced to ensure that we are not in the same situation in the future. The disparity between therapeutic decision making and TNM staging is marked and we would appeal for the radical overhaul of TNM staging to make it fit for the twenty-first century. TNM is central to the management of cancer patients and we must protect and enhance its reputation.