Advances in chemoprevention of head and neck cancer.

Head and neck squamous cell carcinoma is a devastating disease with a poor outcome in advanced stages, accounting for approximately 3% of all malignancies, with an estimated 37200 new cases and 11000 deaths annually in the U.S. Second primary tumors are estimated to occur at an annual rate of 3%-10% and are significant threats to long-term survivors. Chemoprevention is an appealing strategy, and its success has been demonstrated in breast cancer and familial adenomatous polyposis. High-dose retinoids have been shown to be active against oral premalignant lesions and in prevention of second primary tumors in the head and neck. New targets include the epidermal growth factor receptor, cyclooxygenase-2, and other molecular targets. Challenges in future head and neck cancer chemoprevention investigations include achieving long-lasting efficacy with retinoids and/or new agents, and determining the optimal dose and duration of therapy while maintaining acceptable toxicities.