BIOLOGY AND CHEMOPREVENTION OF HEAD AND NECK-CANCER

Head and neck cancer remains a common cause of mortality and morbidity in the United States and throughout the world. in spite of advances i n the management of patients with advanced disease, overall survival i n this group remains poor. Furthermore, although cancer mortality is l ower in patients with early-stage disease, treatment results in signif icant morbidity, and these patients also face the risk of developing a second primary tumor. Chemoprevention is an innovative approach to de crease overall cancer morbidity and mortality using substances that ar e capable of preventing cancer progression. Head and neck cancer is an excellent model for chemoprevention, as its biology is consistent wit h the two concepts important for the development of chemoprevention st rategies: field cancerization and multistep carcinogenesis. Several cl asses of compounds have been evaluated in chemoprevention trials. The most frequently studied agents, the retinoids, were found frequently t o induce remissions in patients with oral leukoplakia. Furthermore, re tinoids prevented progression to malignancy in one randomized maintena nce study. other agents, including beta-carotene and vitamin E, have b een found also to have activity in the management of oral leukoplakia. However, the clinical role of chemopreventive agents in reducing canc er mortality remains to be defined. Two studies, one in head and neck cancer and one in lung cancer, have shown the ability of retinoids to prevent the development of second primary tumors. Current large random ized trials are defining the effectiveness of these agents in reducing the mortality of aerodigestive tract tumors in individuals at high ri sk.