The TNM Classification of Malignant Tumours (TNM) system was designed by Professor Pierre Denoix in the 1940's to assist in the staging of cancerous tumors. The staging system focuses on evaluating the primary tumor, what the tumor has invaded locally, and if the cancer has spread beyond the local area.
This system of diagnosis assists doctors in describing the metastatic progress of a cancer in ways that are meaningful to assisting in prognosis and treatment. It is used by the American Joint Committee on Cancer (AJCC). The staging consists of 3 elements: T, N, M.