Certainly, the most effective means of eradicating cancer is to prevent or delay its occurrence. Therefore, a primary focus of cancer research efforts should be devoted to uncovering mechanisms of cancer initiation, defining new targets for early intervention, and evaluating the efficacy of agents individually and in combination for cancer prevention. Prevention researchers have used mouse models for many decades, particularly employing carcinogen protocols as the means to stimulate consistent tumor formation that provides a readout of efficacy for single or multiple prevention agents. There is now increasing use of genetically engineered mouse cancer models because they reflect the natural histories of cancers at a variety of organ sites, and permit testing of prevention strategies and agents at various stages of the disease development process, and not just tumors.
Natural histories of cancer
Understanding the earliest steps in the development of cancer will help researchers to discover possible chemopreventative interventions. Precancerous states have been targeted for exploration in numerous mouse models, not only for traditional pharmaceutical interventions but also for strategies such as evaluating dietary influences as well. As appropriate models become more refined and better characterized, the promise of using mouse models to evaluate chemoprevention methods will be met.
Types of cancers that have been pursued for increased understanding of the premalignant state using mouse models include pancreatic cancers, skin cancer, lung cancer, breast cancer, colorectal cancer, and others.
Prevention strategies and agents
Researchers have also desired to explore cancer resistant mouse models to learn more about stopping tumorigenesis before it begins. These prevention studies in mouse models could provided extensive value for human health. In addition, understanding the mechanisms of aging and the roles of the immune system may offer directions for further understanding of the steps that lead to cancer, with an eye toward timely interventions to escape or to postpone cancer. Another possible prevention strategy is the development of cancer vaccines, which is being pursued in mouse systems.
Understanding environmental impacts using animal model systems yields important clues that we hope will translate to maintaining human health. A large-scale project to evaluate the influence of various environmental exposures is being performed by the German Mouse Clinic (GMC) efforts. The knowledge gained from the types of challenge tests undertaken as part of this project will provide a helpful foundation for explorations of other models systems as well, including chemoprevention and chemotherapy studies.