Viruses, Immunity, and Cancer

Reading the scientific and medical literature is difficult without feeling swamped by suggested causes of human cancer: genetic factors have been implicated; epidemiological studies based on geographic variations in cancer incidence have suggested a variety of environmental factors [1]; multiple elements in our food and diet have been indicted at various times; and many fashions of western and eastern society have been held to contain factors that increase the incidence of malignant diseases [2]. With this in mind, it is not surprising that virus infection has been associated with the aetiology of cancer; however, this theory deserves attention, since it is supported by a large body of circumstantial evidence, and under strictly controlled conditions, viruses can be shown to induce many forms of cancer in a variety of animal species. These observations have led many authorities to suggest that viruses are aetiological agents of malignant disease in man, but the inability to carry out the experiments that proved the association of viruses and cancer in animals has meant that direct proof of association cannot be made for human cancers.