Head and Neck Squamous Cell Carcinoma with Distant Metastasis: A Systematic Review and Meta-Analysis.

Background/objectives: Distant metastasis (DM), though uncommon at initial presentation, significantly worsens the prognosis of head and neck squamous cell carcinomas (HNSCCs). This review aimed to investigate the occurrence rates, patterns, and implications of HNSCC DM.

Methods: A systematic search was performed in Scopus, PubMed and Web of Science.

Results: Out of 7576 identified titles, 35 studies were included, encompassing 28,193 patients. The pooled rate of DM was 10.01%, with significant heterogeneity existing among the studies (I2: 94.13%). The most common metastatic sites were the lungs, bones, and brain (58%, 15%, 4%, respectively). Treatment modalities varied: overall, 20.4% of patients received radiotherapy alone, 7% underwent chemotherapy, and 4.5% received surgical metastasectomies. Combined treatments accounted for 18.3% of patients. However, 41.3% of patients received no treatment for DM. The median overall survival (OS) after DM diagnosis was 10.1 months. Studies highlighted a 36.3% two-year survival rate for patients with oligo-metastases, compared to the 7.4% rate for those with multiple metastases. At the time of DM diagnosis, half of the studied population presented with locoregional failure.

Conclusions: Advanced imaging techniques and emerging systemic therapies offer hope for improved DM detection and treatment. However, continuous research is essential to develop therapeutic strategies that can enhance survival and improve the quality of life for patients with DM.