Molecular metastases markers in head and neck squamous cell carcinoma: review of the literature.

It is now widely accepted that the presence of lymph node metastases is a negative prognostic factor in head and neck squamous cell carcinoma. It follows that the ability to determine the presence of micro-metastases or the metastatic potential of a tumour at an early stage would condition the therapeutic strategy and evolution of this type of tumour. Prediction of the metastatic potential of head and neck squamous cell carcinoma is still, today, entrusted to clinical and histological evaluation of the tumour. However, the high percentage of relapse in this tumour shows the inadequacy of these parameters in predicting metastatic potential. Furthermore, progress made over the last ten years in understanding the molecular mechanisms involved in the process of neoplastic tumour progression has led to the identification of molecules that can be used as potential prognostic markers of head and neck squamous cell carcinoma. There are many molecules involved in the process of forming metastases. This process represents the final stage of a multistep model, in which alterations occur to genes that are important for growth, proliferation and migration, to which are added variations in the expression of molecules involved in the process of homeostasis of the extra-cellular matrix, of angiogenesis and lymphangiogenesis, favouring tumour invasion and the formation of metastases. This review of the literature shows that the tumour invasion process is associated with numerous molecular alterations that might be used as potential prognostic molecular markers. However, none of these alterations is univocally associated with the metastasization used in clinical practice. Further studies on larger series and on a larger scale, such as genome studies, and preclinical studies on markers used as targets in specific therapies, will provide a valuable contribution to their use in clinical practice in the short term.