Clinical and histopathological risk factors for distant metastasis in head and neck cancer patients

The incidence of distant metastasis (DM) in head and neck squamous cell cancer (HNSCC) is relatively low. Multiple risk factors have been described for development of DM at baseline and after treatment. However, to date, there is no meta-analysis or systematic review investigating the relationships between clinical and histopathological factors and the appearance of DM in HNSCC patients. Among 1,272 eligible articles, 23 met inclusion criteria for qualitative analysis, and 6 for quantitative analysis. The meta-analysis on 5,353 patients showed that hypopharyngeal site, T3-T4 categories, extranodal extension, positive lymph node size > 6 cm, locoregional failure after previous treatment(s) and poor differentiation all significantly increase the risk of DM. According to our results, patients with the above-mentioned clinical and histopathological risk factors should be considered at high risk for DM and therefore submitted to strict pre-treatment assessment and undergo careful post-therapeutic follow-up.