Tnm classification, head and neck

Malignant head and neck tumours are staged according to the TumourNodesMetastasis (TNM) classification, based on criteria recommended by the 'Union International contre le Cancer' (UICC) or the 'American Joint Committee on Cancer' (AJCC). The clinical criteria used for assigning a tumour a particular T-classification are site-dependent; for example in the oropharynx tumour diameter is important, while in the larynx tumoral involvement of laryngeal subsites and impairment of vocal cord mobility are important criteria. It is generally recognized that the validity of any classification is dependent on the diagnostic methods employed. Both the UICC and the AJCC state that imaging is valuable in the diagnostic investigation, but the guidelines do not indicate precisely when imaging should be used, nor what technique should be chosen. Modern radiological imaging methods assist in pretreatment planning by better defining the extension of infiltrating head and neck tumours and by detecting subclinical adenopathies.

Concerns have been expressed about the weakness of the TNM classification with respect to laryngeal cancer, and other head and neck cancer sites, as the cure rates reported in the literature vary and prognosis is not sufficiently related to the TNM values.

Recently, it has been shown that a quantitative analysis, with calculation of tumour volume from CT images, offers important complementary information to the clinical examination regarding the prognosis of head and neck tumours after curative radiation therapy. There are indications that functional imaging methods (e.g. measuring tumour perfusion rate or tumour oxygenation level) may also provide additional information.

RH