Proposal for modification of the TNM staging classification for cancer of the oral cavity

Aim. The prognostic value of the TNM and pTNM classifications currently use d for tumours of the oral cavity is unsatisfactory. A better classification should he aimed at as today's definition of T4 leads to overclassification of many tumours and today's definition of N3 results in too few lymph node s in this group. Until 1987 the grade of fixation of lymph-nodes was part o f the N-classification for oral cancer as it is currently used in the N-cla ssification of breast cancer. Methods. From 1987 to 1991 the DOSAK tumour registry has stored 1532 primar y cases of cancer of the oral cavity from 23 hospitals, Crosstables were ap plied to outline the classification rule for clinical and histopathological T and N based on important factors (T: tumour diameter and thickness; N: l ymph node diameter and grade of fixation; pT: histopathological tumour diam eter and thickness; pN: number of lymph nodes involved by the tumour), A Co x model was calculated and combinations of similar prognostic estimates wer e summarized to the same clinical and histopathological T and N. It was aim ed at separating categories and achieving equivalent clinical and histopath ological T classifications and group frequencies. In a final step a clinica l and histopathological stage grouping can be proposed. Results. The gradation of the survival rates shows a marked separation betw een the T, N and stage categories. The distribution of T, N and stage categ ories was more uniform when applying the new classification. (C) 1999 Europ ean Association for Cranio-Maxillofacial Surgery.