Prognostic and predictive factors in recurrent and/or metastatic head and neck squamous cell carcinoma: A review of the literature

The pattern of clinical behaviour and response to treatment of recurrent and/or metastatic head and neck squamous cell carcinoma is heterogeneous. Treatment strategies that can be employed vary from potentially curative salvage surgery and re-irradiation to palliative systemic therapies and best supportive care. The advent of new therapeutic options, in terms of more sophisticated surgical approaches and techniques, highly conformal and precise radiation techniques and immunotherapy may offer improved control of disease and longer survival. Moreover, the epidemiological changes during the last decades, including the increase of human papilloma virus-related oropharyngeal primary tumors, are also reflected in the recurrent and metastatic setting. In this complex context the identification of predictive and prognostic factors is urgently needed to tailor treatment, to increase its efficacy, and to avoid unnecessary toxicities. A better knowledge of prognosis may also help the patients and caregivers in decision making on the optimal choice of care. The purpose of our review is to highlight the current evidence and shortcomings in this field.