- Histologically or cytologically proven squamous cell carcinoma of th head and neck or its variants. Primary tumor sites eligible include nasopharynx, oral cavity, oropharynx, hypopharynx, larynx, or unknown primary SSCHN. Although they have squamous histology, tumors of the skin, nasal cavity and paranasal sinuses are excluded because their responsiveness to chemotherapy and radiotherapy may differ.