[TNM staging system of lung carcinoma: historical notes, limitations and controversies]

The TNM System as originally proposed by Denoix in 1946, provides a consistent, reproducible description of the anatomic extent of disease in cancer patients at a specific time in the life history of the cancer. C.F. Mountain first adapted this classification to lung cancer in 1973 on behalf of AJCC. In 1986 he presented the "New Intl. Staging System for Lung Cancers" mainly based on a 13 yr experience of the previous one, which was accepted world-wide through a round of international consensus meetings held in 1985. Clinical Staging is the best estimate of disease extent made prior to the institution of any therapy; Surgical-pathological Staging is the classification of disease extent as determined from pathological examination of resected specimens. Accordingly, once the diagnosis is made, it is necessary to stage accurately the tumour determining the size and location of the tumour (T status), the presence or absence of lymphnode involvement (N status), and whether the tumour is metastatic to distant sites (M status). Moreover the uniform staging criteria for lung cancer will assure for each patient the better selection of treatment, the evaluation of operability, the need for adjuvant therapy, as well as the estimation of prognosis. Equally important is the resultant ability to compare the outcome of treatment protocols from different centres. More recently C.F. Mountain has added to the Staging System a new standard logic or "convention" for classifying infrequently observed presentations of lung cancer with which the standard rules of Staging System itself don't fit. These conventions are based on empiric expectation for treatment selection and survival that are similar to those for the Staging definitions, which are based on actuarialsurvival data. Many different types of tumour such as multiple masses, synchronous multiple primitives, discontinuous tumour foci in visceral or parietal pleura as well neoplastic involvement of various mediastinal structures, could be now staged with a major benefit for their treatment protocols. In conclusion the Staging System represents today a standard clinical methodology which basically helps in a better clinical approach to lung cancer even if it cannot fully cover and consider all the innumerable manifestations of the tumor. Therefore, if it is true that in the near future the new molecular predictors of prognosis are expected to measure more deeply the extent of disease, for the present time the International Staging System still continues to act as the best common method for measuring prognosis.