When discussing bladder cancer, it is useful for both doctors and patients to describe its size and extent in a standardized manner. Indeed, an international staging system exists, known as the TNM staging system. Each letter classifies a given cancer with respect to the size or or as in the case with bladder cancer, the depth of the primary tumor(T); the presence or absence of lymph node metastases(N); and the presence or absence of metastases to other organs(M). Below is a list of the official TNM staging system with a pictorial representation of a Ta, T1, T2b, and T3b bladder tumor as examples.