[The new TNM classification in lung cancer]

This paper presents the new TNM classification in lung cancer and its history. Seventh edition of tumor, node, metastasis (TNM) classification in lung cancer has been published by the International Union Against Cancer (UICC) and the American Joint Committee on Cancer (AJCC) at the beginning of 2009. The changes were based upon the results of the international project of the International Association for the Study of Lung Cancer (IASLC). The database included 81.495 patients from the entire world (68.463 with non-small cell lung cancer and 13.032 with small cell lung cancer) treated with various modalities between 1990 and 2000. The collected data were validated internally and externally. The tumor size was considered of prognostic relevance: T1 tumors were subdivided into T1a (≤ 2 cm) and T1b (〉 2 cm - ≤ 3 cm), T2 tumors into T2a (〉 3 cm - ≤ 5 cm) and T2b (〉 5 cm - ≤ 7 cm), and T2 tumors 〉 7 cm were reclassified as T3. Tumors with the additional nodules in the same lobe as the primary tumor were classified as T3, those with additional nodules in another ipsilateral lobe - as T4. There were no changes in N category. In the M category, M1 was subclassified into M1a (contralateral lung nodules and pleural dissemination) and M1b (distant metastasis). Large T2 tumors (T2bN0M0) were upstaged from IB to IIA, small T2 tumors (T2aN1M0) were downstaged from the IIB to IIA and T4N0-N1M0 - from IIIB to IIIA. The TNM classification was also recommended for small cell lung cancer instead of previously used categories of limited and extensive disease.