Women who are infected with a virus called the bovine leukemia virus (BLV) may face an increased risk of breast cancer, according to a recent study.
In the study, researchers tested the breast tissue of about 240 women for BLV, and found that 59 percent of the samples from women who had breast cancer showed signs of BLV. Only 29 percent of the samples from women without breast cancer showed signs of the virus.
The researchers’ analysis of the data revealed that the odds of having breast cancer, when taking other risk factors into account, were three times higher if BLV was present — an increase that’s higher than those of several other well known risk factors for breast cancer, including drinking alcohol, being obese and using hormone treatments after menopause, the study said.
BLV is frequently found in cattle herds throughout the United States, infecting the animals’ blood cells and mammary tissues. Most cows do not become sick from the virus, although a very small percentage do develop cancer of the lymph system. [6 Things Women Can Do to Lower Breast Cancer Risk]
Researchers are still working to determine how the virus is transmitted to people. It’s possible that dairy products and beef may be a source of infection, the researchers said. The new study did not determine how BLV infected the breast tissue samples.
“The most important thing now is to learn how humans get the virus,” said Gertrude Buehring, the lead author of the new study and a professor of virology at the University of California, Berkeley’s School of Public Health. “Is it coming from cattle, or is it coming from other humans?”