Mouse models that mimic human disease play a vital role in understanding the etiology (cause and origin) of cancer. Results of mouse model studies lend evidence toward the next step in biomedical research that leads to early detection of cancer, new cancer drugs, new combinations of treatments, or new methods such as gene therapy.

Scientists use mouse models for investigating mutations in humans triggered by environmental agents, drugs, aging, and diet. Mutations cause a random change in a gene, or chromosome, that results in a new trait or characteristic that can be inherited. The genetic similarity of mice to humans accounts for mice being a good experimental model to study cancer. Also, human tumors can be grafted onto the mouse without rejection. This procedure allows for the study of specific human cancers, as well as the testing of various medical applications.

One particular area of interest in examining the impact of the external factors on cancer development is the field of epigenetics, which is the study of inherited changes in either physical appearance or in how genes are expressed, that are caused by mechanisms other than changes in the underlying DNA sequence.