TNM CLASSIFICATION OF MALIGNANT TUMOURS: HISTORY, PRINCIPLES, PRACTICAL APPLICATION

In oncology the TNM staging system is a universal means of coding the malignant tumour extension, the assessment of anticancer therapy and the disease prognosis. The main classifying criteria are: the characteristic of the extent of primary tumour (T), the presence of regional (N) and distant metastases (M), the histological type of a tumour and the grade of its differentiation (G). The «clinical reading» of the TNM provides the practice of using the combination of T, N, and M categories in various clinical situations. The additional and optional classification criteria are: m — multiple primary tumours, r — recurrent tumour, R — residual tumour, the patient’s performance status (ECOG), the concentration of the tumour biochemical, immunologic and molecular markers, L — the tumour’s lymphatic invasion, V — the tumour’s venous invasion, Pn — perineural invasion, isolated tumour cells (ITC), micrometastases (mi), C — the certainty factor, which reflects the validity of classification. The division of tumours according to WHO/RECIST classification into «target lesions» and «nontarget lesions», which is based on CT/MRI imaging scans, allows getting the exact grade of entire tumour burden, and helps to assess the effectiveness of anticancer therapy («tumour response») in the further diagnostic checkups. The TNM system is an evolutional one; it is expected, that the malignant tumour classification based on modern diagnostic technologies will be developing towards molecular-genetic criteria.



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