Head and neck cancers form in the nasal cavity (the hollow space inside the nose), sinuses, lips, mouth, salivary glands, throat, and larynx (voice box). Most head and neck cancers begin in squamous cells (thin, flat cells that line the moist surfaces of the head and neck). The most important factors that increase a person’s risk of developing head and neck cancers are tobacco use, heavy alcohol use, and infection with certain types of high-risk human papillomavirus (HPV).