Analysis of Animal Carcinogenicity Data
Animal carcinogenicity experiments are employed to test the carcinogenic potential of drugs and other chemical substances used by humans. Such bioassays are conducted in animals at doses that are generally well above human exposure levels, in order to detect carcinogenicity with relatively small numbers of animals. Animals are divided into several groups by randomization and treated with a test compound at different dose levels. A typical carcinogenicity study involves a control and 2 to 3 dose groups of 50 or more animals, usually rats or mice. Typically, a chemical is administered at a constant daily dose rate for a major portion of the lifetime of the test animal, for example, for 2 years. Sometimes, scheduled interim sacrifices are performed during the experiment. At the end of the study, all surviving animals are sacrificed and subjected to necropsy. For each animal in a given dose group, the age at death and the presence or absence of specific tumor types are recorded. Groups of animals are compared with respect to tumor development.
KeywordsDose Group Trend Test Occult Tumor Nonparametric Maximum Likelihood Fatal Tumor
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