Evaluation of the validity of the 1997 International Union Against Cancer TNM classification of major salivary gland carcinoma

BACKGROUND, The TNM classification (International Union Against Cancer) of salivary gland carcinoma was revised in 1997. In this study, the authors ha ve evaluated the validity of this new TNM classification and clinical stagi ng in 1683 patients with parotid gland carcinoma. METHODS. Reclassification was conducted according to the new classification based on the clinical data of 1683 patients registered to the salivary gla nd division of the Japanese Joint Committee on TNM classification. The 5- a nd 10-year survival rates according to TNM classification were calculated f or 1074 patients whose prognosis could be followed up. Finally, the distrib ution of the total patient population was analyzed using the new staging an d the survival curves for each disease stage. RESULTS. The variance of the patients for T1 to T4 was appropriate using th e new T classification. The 5- and 10-year survival rates corresponded well to the degree of progression of TNM. However, there were only nine patient s with Stage III, and marked nonuniformity in the staging was observed. The separation of the survival curves for each stage was not clear, and no sig nificant differences between the survival curves of Stages II and III and S tages III and IV were observed. When the authors classified T1N1M0, T2N1M0, T3N1N0, and T4N0M0, which have 5- and 10-year survival rates similar to St age III, distribution of patients and separation of the survival curves in each stage improved markedly. CONCLUSIONS. The results of the current study confirm that the new TNM clas sification system is valid. However, a significant problem was observed wit h respect to the new clinical staging. The authors propose that T1N1M0, T2N 1M0, T3N1M0, and T4N0M0 be classified as Stage III. Cancer 2000;99:1664-9. (C) 2000 American Cancer Society.