Head and Neck Field Carcinogenesis

This chapter reviews the evidence for the field cancerization process during multistep head and neck tumorigenesis, and discusses the implications of such a process in the clinical management of individuals at high risk for first and second head and neck primary tumors. Tumors of the head and neck have been proposed to reflect a field-cancerization process whereby the tissue region is thought to be exposed to carcinogenic insult such as tobacco products and alcohol and is at increased risk for multistep tumor development. The concept of field cancerization in the setting of head and neck cancer is important because it has critical implications for assessing the risk of first and second primary tumors and thus can have a profound impact on the clinical management of individuals with premalignant lesions, of individuals who have been definitively treated for a first primary tumor and remain at high risk for developing a second primary tumor, and of individuals presenting with either a recurrence or a second primary tumor. The field cancerization process in the head and neck epithelium is manifested by clinically detectable lesions prior to cancer development, progressive histologic changes, and alterations of genetic and phenotypic markers in the epithelial cells. The development of targeted approaches for both prevention and therapy will require improved understanding of the process of head and neck tumor development, as well as further characterization of the specific molecular events that underlie the tumor phenotype.