Neoplastic Disease
Neoplastic disease in the rat, as in most species, increases dramatically with increasing age. Many genetic and environmental factors influence the development of neoplasia, and attaining an understanding of these factors and their control is critical for scientists who use the rat in the laboratory setting. This chapter discusses spontaneous and induced neoplastic lesions in the rat. The incidence of spontaneous and induced cancer in the rat is heavily influenced by both genetic and environmental factors. Diet is one of the more important environmental factors that contribute to variability in cancer incidence. Hereditary cancers have been important in the understanding of neoplasia. The genetic changes responsible for familial cancers are often the same as those responsible for the more common spontaneous sporadic forms of neoplasia. Spontaneous mutations in cancer susceptibility genes and genetic predispositions to chemically-induced neoplasia have provided important tools for the study of cancer in rats; however, it will soon be possible to manipulate the rat genome and create a manner very analogous to that used for genetically oncogenesis models in engineered mice.
