Angiogenesis in oral cancer.

Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy that develops after years of chronic exposure to alcohol and tobacco products. Exposure to these agents results in alterations of genes that are important in the regulation of various cellular functions. This loss of regulation allows the tumor cells to survive and grow in an unchecked manner by allowing the cells to perform functions that contribute to the growth of the tumor. Some of these important changes include the acquisition of immortality and the ability to invade tissue and/or metastasize to other sights, as well as acquiring the ability to induce angiogenesis. Angiogenesis, the growth of new blood vessels from pre-existing ones, is a complex phenomenon that is absolutely required for the continued growth and survival of solid neoplasms. Without new blood vessels to provide nutrients and remove waste, tumors would be unable to grow larger than 2-3 mm in diameter. Therefore, one could envision its potential role in both the treatment and prevention of malignancies such as HNSCC. The concept of chemoprevention is extremely important in HNSCC since patients often develop multiple independent lesions throughout the mucosa of the upper aerodigestive tract. Therefore, the comprehensive treatment of this disease must address not only the initial primary neoplasm, but also prevent the progression of the premalignant lesions lurking throughout the rest of the mucosal surfaces. This review will outline the basic changes that occur in tumor cells that result in the switch to angiogenic phenotype. In addition, it will discuss the present status of using antiangiogenic agents in the treatment of cancer. Finally, this paper will present a rationale for the use of multiple antiangiogenic agents as a means of developing new chemotherapeutic and chemopreventive protocols that may result in reduced patient toxicity while maintaining similar clinical efficacies.