California – A study showed for the first time that the Bovine Leukemia Virus (BLV) may be associated with human breast cancer. The research suggests that the probability of a person developing breast cancer is significantly higher if BLV is present.

For the study, conducted by UC Berkeley researchers and published in the journal PLOS ONE, scientists analyzed tissue from 239 women seeking the presence of BLV. They compared samples from women who had breast cancer with women who have never suffered from the disease.

Results showed that 59 percent of breast cancer patients had evidence of exposure to BLV. On the other hand, only 29 percent of samples from women who never had breast cancer showed trails of BLV. When the data was analyzed statistically, the odds of having breast cancer if BLV was present was 3.1 times greater than if BLV wasn’t.

Credit: LaboratoryEquipment

“The association between BLV infection and breast cancer was surprising to many previous reviewers of the study, but it’s important to note that our results do not prove that the virus causes cancer,” stated Gertrude Buehring, a professor of virology in the Division of Infectious Diseases and Vaccinology at UC Berkeley’s School of Public Health and study lead author, in a University’s statement.

BLV is easily transmitted among cattle through infected blood and milk, causing diseases in less than 5% of the infected animals, reaching its blood cells and mammary tissue.

In 2007, after the US Department of Agriculture surveyed bulk milk tanks, the agency found that 100% of dairy operations with large herds of more than 500 tested positive for BLV. Dairy operations with small herds of less than 100 cows tested positive for BLV 83% of the time.

Previous studies

What has been unclear until this research was whether the virus could be found in humans or not. This report is a relevant advance as it proves wrong a long-held belief that BLV could not be transmitted to humans.

“Studies done in the 1970s failed to detect evidence of human infection with BLV. The tests we have now are more sensitive, but it was still hard to overturn the established dogma that BLV was not transmissible to humans. As a result, there has been little incentive for the cattle industry to set up procedures to contain the spread of the virus,” said Buehring.

Promising Expectations

It is known that there are several viruses that ultimately may derive into cancer. For instance, Hepatitis B is known to originate liver cancer, as well as the Human Papillomavirus (HPV), which can lead to cervical and anal cancers. Fortunately, vaccines have been developed for both those viruses and are used to prevent cancers associated with them.

Buehring added that, “If BLV were proven to be a cause of breast cancer, it could change the way we currently look at breast cancer control. It could shift the emphasis to prevention of breast cancer, rather than trying to cure or control it after it has already occurred.”

Source: PLOS ONE