Revision of classification of laryngeal cancer, is it long overdue? (Proposals for an improved TN-classification)

The TNM-classification of laryngeal carcinomas of the UICC contains a number of weaknesses which diminish their prognostic relevance. Based on clinical observations and microscopic investigations of surgical specimens, several changes are proposed to improve the existing TN-classification. The larynx is subdivided by the UICC into the supraglottic, the glottic and the subglottic main area and their tumours. There are embryological, anatomical, functional and oncological reasons to divide the larynx into two main areas only--the supraglottis and the glottis (vocal folds) without any further subsites and to abandon a separate group of subglottic tumours. The T size of a tumour should not be assessed according to the extent of an ill-defined anatomical region, but measured in millimetres of greatest surface extent only. The T2 category of vocal fold tumours should not contain those which lead to an inhibited mobility of the fold. All tumours with reduced vocal fold mobility or fixation should be classified as T3 or T4 according to the dimension of invasion. Post-operative pathological examinations (pT/pN) allow an assessment of the true extent of a tumour in three dimensions. A validation study using a 'metric' TpT-classification shows very distinct groups of tumours with a significantly different prognosis from Tis 1 to T4. Studies of lymph node metastases in the neck have shown that, number, size, site of metastasis and the presence of extracapsular tumour spread have a significant influence on the prognosis. An improved N/pN-classification taking these factors in consideration is proposed.