The prediction of outcomes of oncologic treatment and prognosis is a fundamental need in the minds of patients and physicians alike. William Halsted, the father of surgical oncology, theorized that cancer progression follows an orderly, stepwise process beginning from primary tumor formation to distant theorized metastasis, passing through regional lymph nodes (1). In 1905, Steinthal in Germany first attempted to clinically stage breast cancer based on Halsted's theory (2). This simple concept of stepwise tumor progression was widely used in the first part of the 20th century and has essentially shaped the way we view and comprehend the behavior of a malignant tumor. It has also influenced the way we diagnose cancer, treat it and predict its course. The first systematic approach to stage cancer in a consistent way was done at Institut Gustave Roussy by Pierre Denoix. From 1942 to 1952, Denoix developed a system to stage solid malignancy based mainly on three anatomic characteristics: tumor (T), lymph node spread (N) and distant metastasis (M) (3). In 1953, a Special Committee on Clinical Stage Classification was established by the International Union Against Cancer (UICC) under the leadership of Denoix (4). In 1959, the American Joint Committee on Cancer (AJCC) was established to “formulate and publish systems of classification of cancer, including staging and end results reporting, which will be acceptable to and used by the medical profession for selecting the most effective treatment, determining prognosis, and continuing evaluation of cancer control measures” (5). After an initial course that was independent of each other and often contradictory, both organizations have worked in collaboration through the publication of the UICC/AJCC TNM Classification since 1987, and this has helped to standardize the way cancer is staged and results of treatment are reported around the world (6).