Implications of animal cancers to human neoplasia: Epidemiologic considerations

Abstract

Wide variation in biologic and ecologic characteristics of the various animal species suggests opportunity for unique epidemiologic study of cancer; such studies may be designed to capitalize on species diferences which permit the eflective segregation and evaluation of factors suspected in the etiology of cancer in all species, including man. Epidemiologic exp(oitation of animal cancer models in the interests of the human problem is limited by the quality and quantity of disease occurrence and risk population data. The automated, nomenclature-based Veterinary Medical Data Program of the National Cancer Institute (USPHS) has been adopted by a number of institutional veterinary college hospitals in the US and Europe, and serves as a source of derailed information on the occurrence of animal diseases seen at the participating facilities. Utilization of the case history relativr-odds study design promises to facilitate epidemiologic investigation of cancer in animals. Reported clusters of bovine lymphoma in dairy herds are unexplained and currently under study in an effort to evaluate possible genetic and viral factors. The analytic complications characteristic of human cancer cluster investigations are compounded in the case of animal cancer cluster studies. While a postulated relationship between the occurrence of cancer in nian and animals is academically attractive, no such association has been demonstrated to date. Epidemiologic investigation of animal cancer models, while warranted and possible, must be designed so as to meet with limitations of available data. By any measure, the magnitude of the scientific assault directed t o the solution of the human cancer problem is without precedent in the history of medical science. While progress t o date is, in many respects, impressive and represents a great advance in the development of sophisticated research techniques, the basic problems of cure and prevention of human neoplastic disease remain unsolved. The possibility that cancer represents a large group of diseases, each of which may require resolution of the unique problems involving interaction of etiologic factors and conditional susceptibility, is, to say the least, a rather sobering thought. The profound complexity of the cancer problem warrants recruitment of talent from many different technical and professional areas as well as exploitation of all realistic research opportunities.When reduced to an arbitrary and somewhat imperfect classification, most cancer research efforts can be categorized as either laboratory or epidemiologic in nature and method. Laboratory scientists conduct experiments which permit

Possible benefits to veterinary medicine of considering the dog as a model for human cancer

“…The annual incidence rate of bone tumours in the dog was found to be seven times higher than in man in a defined geographical area in California (Dorn,19 76) and, apart from species-corrected age occurrence, the biological behaviour of osteosarcoma is remarkably similar in the two species (Owen, 1969;Brodey, 1979). It is well recognized that the larger breeds of dog are more susceptible to the disease (Tjalma, 1966;Brodey & Riser, 1969) whilst children of larger skeletal size are also at greater risk of developing boney malignancies (Fraumeni, 1967). Medullary infarction (Brodey & Abt, 1976;Gall et a/., 1978) and metal implants have been shown to predispose to bone tumours in both man and dog and, in each, it is the metaphyseal regions of the major weight-bearing long bones that are the prime sites of origin (Brodey, 1979;Dahlin, 1967).…”