[Justification of the TNM classification system in lung carcinoma]

The clinical TNM classification system allows improved exchange of information, is an aid in tumor staging and establishing treatment schedules, assists in assessing prognosis and forms the basis of cancer registration. New elements in the last edition of classifications are stage T4, which means a tumor invading the mediastinum, the heart, the great vessels, the trachea, the esophagus, vertebral bodies, the carina or the pleural space, and stage N3, which includes mediastinal, contralateral hilar, scalene and supraclavicular lymph node metastases. Both stages rule out surgical treatment. Mediastinoscopy is advised in the case of lymph nodes in thoracic CAT of greater than or equal to 1.5 cm diameter. There is evidence that most peritumoral infiltrations consist in T lymphocytes, presenting the host's immunological reaction against tumor tissue. In the context of tumor staging such phenomena may be of prognostic significance.