The viral etiology of cancer.A realistic approach

Abstract

The etiology of cancer resembles that of many other diseases in that multiple factors may be required. Because of this, the role or viruses in the etiology of human cancers is especially difficult to assess. When animal tumor systems were used as models, the roles of various predisposing characteristics in virus on‐cogenesis were elucidated. Extrapolation of these findings to the human diseases suggests the importance of genetics, age, hormones, immune competence, and stress in determining susceptibility to tumor development in individuals infected with an oncogenic virus. The importance of cofactors in induction of those human tumors most strongly associated with virus infection, including Burkitt's lymphoma, nasopharyngeal carcinoma, cervical carcinoma, acute myelogenous leukemia, and breast cancer, is reviewed. Understanding of the role of these cofactors in virus carcinogenesis may lead to disease prevention through elimination of one or more of the cofactors. Cancer 40:419–429, 1977.

Conversion of Herpetic Lesions to Malignancy by Ultraviolet Exposure and Promoter Application

“…Certain herpes viruses have been associated with human neoplasias (Burkitt's lymphoma and nasopharyngeal carcinoma), but the role of HSV in the development of human cancer has been very difficult to demonstrate due to the frequency with which this virus is found in the general population and the relative rarity of squamous cell carcinoma development in the same population (Rapp & Reed, 1977). The transforming event may be quite infrequent due to the inefficiency of the 'oncogenic' virus or the extreme sensitivity of the host defence mechanisms.…”

Tumorigenic transformation induced by a specific fragment of DNA from herpes simplex virus type 2.

“…Transformation appears to be mediated by fragment(s) of the HSV-2 genome: (i) mechanically sheared HSV-2 DNA (Mr 9 X 106) induces neoplastic transformation at a frequency identical to that observed with native DNA (4), (ii) hamster cells transformed by UV-irradiated HSV-2 retain a fraction (8-32%) of the viral DNA sequences (5), and (iii) virus transforming activity is more resistant than its infectivity to radiation damage (1,2). However, the oncogenic fragment in the HSV-2 genome has not yet been identified.…”

Some aspects of the role of viruses in cancer

“…The oncogenic viruses of animals include both RNA and DNA viruses classified in a number of different groups (Green, 1977). Researchers (Todaro and Huebner, 1972;Klein, 1972); however, the strongest case at the present time is for DNA viruses, and the methods used for these investigations are animal studies, the transformation of animal and human cells grown in tissue culture, the detection of virus or virus-specific nucleic acid in cancer cells and the presence of viral antibodies in patients with malignant disease (Rapp and Reed, 1977 (Lucke, 1938;Churchill and Briggs, 1967), and at least 2 monkey herpesviruses which can induce lymphomas when inoculated into monkeys of a different species. In addition, the herpesviruses include 2 infective agents of man that have been implicated in human malignant disease; these are the Epstein-Barr virus associated with Burkitt's lymphoma (Zur Hausen, 1975), and herpesvirus type 2 which has been associated with carcinoma of the cervix (Nahmias et al, 1970 (Habel and Eddy, 1963;Potter and Oxford, 1970 (Pope and Rowe, 1964) or by complement-fixation tests (Black et al, 1963).…”