Viruses were demonstrated to cause neoplasms in lower animals as early as 1909 (Ellermann and Bang, 1909). Several decades later, Gross reported the presence of a virus-like agent in mice capable of causing salivary gland carcinomas when inoculated into newborns (Gross, 1953). The association of viruses with human cancer was not seriously appreciated until a report by Epstein and associates (1964) described the presence of virus particles in lymphoblasts isolated from a lymphoma of the type originally reported by Dr. Dennis Burkitt (1958). Burkitt had observed that the lymphoma bearing his name occurred primarily in children in certain parts of Africa. Because of this, he proposed an infectious origin for the neoplasm (cf. Henle et al., 1979) based largely on this peculiar geographic distribution, which was similar to some other infectious dis- eases seen in Africa. Since the discovery of the Epstein-Barr virus (EBV) in 1964, there has been an almost exponential increase in the number of viruses shown to cause specific human cancers. Moreover, the number of people at risk from infections of such oncogenic viruses and subsequent risk of neoplasia is well into the millions throughout the world. Table 12.7 lists vi-
Table 12.7 Viruses and Human Cancer and Related Disease
ruses known to be causative or at least associated with the development of a variety of human neoplasms as well as specific nonneoplastic diseases that may be indirectly associated with an increased development of neoplasia, such as the acquired immunodeficiency syndrome (AIDS). In the table, the IARC classification of carcinogenic risk is given where it has been published. Where the IARC has not made any definitive statements or the condition is not a neoplasm, the codes C for causative and A for associated are given. Each of these agents is considered briefly in the remainder of this chapter.