What Are Animal Models of Cancer

The complexity of the many diseases that we call cancers and the urgent need for improved patient outcomes provide the impetus to employ animal models of cancer.  Medical researchers use animals for a variety of reasons.  Primarily they are comparative living systems that allow researchers to discover the underlying basis of how and why cancers arise, why primary tumors metastasize, and how various kinds of preventive interventions and treatments can be used to stop the progression of cancer, or the growth and spread of tumors, and prolong patient lives.

Studying Similarities

While research comparing the phenotype of animal cancers to human cancers has revealed some differences, there are many similarities. Similarities in animal models are studied for the following reasons:

• Discovering and testing new therapies to improve patient outcomes.

• Finding better ways to detect cancers at the earliest stages, when malignancies are most curable.
• Assessing fresh approaches to cancer prevention so that cancers do not arise or so that early stages of cancer do not progress to tumors.
• Determining why some individuals are at higher risk for developing cancer, are less responsive to therapy, or are more likely to develop therapy-limiting toxicity. 

Studying Differences

In-depth examination of differences between cancer in animal models and in humans often provides unexpected insights into human cancer biology that would be unobserved if only similarities are examined.

Cancer Model Differences

Cancer models fall into several categories:

• Animals in which cancers occur spontaneously without any alteration of the animal’s genes or initiation of cancer by chemical treatments.

• Animals whose genes are altered so that they develop spontaneous tumors of the same types and with similar properties as the tumors which those altered genes cause in humans.

• Animals that develop spontaneous tumors if they are exposed to environmental factors, such as chemicals or radiation.

• Animals whose natural, unaltered genetic makeup permits researchers to identify the genes that generate susceptibility to cancer development. 

The utility of the models varies by species, by available research reagents and tools to support the studies, and by similarity to the human situation.  The most commonly used animal cancer models are rodents - mice and rats.  Other cancer models include hamsters, rabbits, dogs, cats, livestock, and fish. 

For additional details about the various models that are developed and used, explore the items in the left-hand navigation features on this page.