Brain metastasis from squamous cell carcinoma of the head and neck: a review of the literature in the genomic era.

Squamous cell carcinoma of the head and neck (HNSCC) affects nearly 500,000 individuals globally each year. With the rise of human papillomavirus (HPV) in the general population, clinicians are seeing a concomitant rise in HPV-related HNSCC. Notably, a hallmark of HPV-related HNSCC is a predilection for unique biological and clinical features, which portend a tendency for hematogenous metastasis to distant locations, such as the brain. Despite the classic belief that HNSCC is restricted to local spread via passive lymphatic drainage, brain metastases (BMs) are a rare complication that occurs in less than 1% of all HNSCC cases. Time between initial diagnosis of HNSCC and BM development can vary considerably. Some patients experience more than a decade of disease-free survival, whereas others present with definitive neurological symptoms that precede primary tumor detection. The authors systematically review the current literature on HNSCC BMs and discuss the current understanding of the effect of HPV status on the risk of developing BMs in the modern genomic era.