Could Bovine Leukemia Virus be a Cause of Breast Cancer?
As many as 37% of breast cancer cases may be attributable to exposure to the bovine leukemia virus. The incidence of breast cancer continues to increase worldwide. In the United States, this amounted to a 40% increase in the incidence by the turn of the century. Presently, the main approach to preventing mortality is early detection and treatment. That’s important, but why not focus more on primary prevention—protecting people from risk factors so they don’t develop breast cancer at all? “Overall, it is estimated that 20% of all human cancers have an infectious origin.” Viruses can trigger cancer by turning on cancer genes or turning off cancer-suppressing genes, but they can also contribute to tumor formation just by causing chronic inflammation. Currently, cancer-causing viruses are considered “the major plausible hypothesis for a direct cause of human breast cancer.” How did we get here? It all started about 40 years ago when a professor of virology at UC Berkeley learned ...