Classification of lung cancer: first experiences with the new TNM classification (4th edition).

In January 1987, the 4th edition of the TNM classification for malignant lung tumours by the International Union Cancer (UICC) came into effect. Thus, for the first time, a uniform worldwide staging system for lung cancer became available. In order to validate the new TNM definitions for lung cancer the data of 3,000 patients were analysed prospectively. Several items were examined: 1) the agreement between clinically (TNM) and pathologically (pTNM) confirmed classification; 2) the value of the various diagnostic techniques estimating the pathologically confirmed classification; 3) the influence of the TNM definitions on separating distinct prognostic groups. With regard to the primary tumour (T), clinical and pathological classifications were identical in 64%; for lymph node involvement (N) the agreement was 48%; for distant metastases it was 90% and for the stages it was 55%. As for the primary tumour (T) the accuracy of radiography (59%) was nearly identical to computed tomography (58%). Both techniques were less precise in determining the extent of lymph node involvement (computed tomography 50%, radiography 43%, correct assessments). The statistically significant differences in prognosis for the various T-, N- and M-categories as well as for the stages could be confirmed. By the new 1987 TNM definitions (4th edition) for lung cancer international conformity became feasible as well as practical, and the improvement in its prognostic relevance provided, therefore, a more reliable basis for establishing guidelines for individual oncological concepts of therapy.