In Pursuit of a Human Breast Cancer Virus, from Mouse to Human

For decades researchers have been fascinated with the idea that human breast cancer might be caused by a virus. This idea derives primarily from the mouse model, the only naturally occurring mammary cancer in an animal for which the cause is known. We briefly review the hallmarks of mouse mammary cancer and its causative virus to set the stage for discussion of possible links with human breast cancer. There are numerous comprehensive reviews of the mouse mammary tumor literature, a few of which have been resources for this chapter (1–5).