Treatment section: Head and neck squamous cell carcinoma most commonly affects the oral cavity, oropharynx, and larynx. Traditional risk factors include tobacco, alcohol, and more recently high-risk strains of human papilloma virus (HPV). The mainstay of treatment includes surgery, radiation, and cytotoxic chemotherapy. Recent updates to diagnosis and staging criteria as well as primary treatment modalities are reviewed below for each head and neck subsite.