EDITORIAL Outcome Prediction and the Future of the TNM Staging System

The prediction of patient prognosis has always been essential to the practice of medicine. By the early 20th century, Halsted (1) and others believed that solid tumors spread contiguously over time through a series of stages, from the primary tumor site, through the lymphatics, to distant organs, with each stage con-ferring an increasingly poor prognosis. A corollary of this view, supported by later research, was that, at diagnosis (clinical tumor–node–metastasis [TNM] stage) or after surgery (patho-logic TNM stage), tumor size or location (T), regional lymph node involvement (N), and distant metastases (M) were indices of disease spread and could be used to predict patient outcome. In 1953, the French surgeon Pierre Denoix proposed to the Union Internationale Centre le Cancer that these three factors be standardized and integrated into a prognostic system that could be used, with some accommodation for anatomic site, across al