Researchers from UC Berkeley and UC Davis have uncovered an association between the presence of bovine leukemia virus in cattle and breast cancer in humans. From the participants, they found that 59 percent of breast cancer samples had evidence of exposure to BLV, while 29 percent of the tissue samples from women who never had breast cancer showed exposure to BLV.
The new study now shows that, statistically, the odds of having breast cancer if BLV were present were 3.1 times greater than if BLV were absent. There is need for further investigation in order to actually confirm if BLV causes breast cancer or not.
“(Our study) overturned a 30-year dogma that humans did not get infected with this virus and it was not transmissible from cattle”, Buehring said.
Researchers studied BLW presence in the breast tissue samples from 239 women. The same group of researchers at the University of California Berkeley involved in the new study also found last year that BLV could be transmitted to humans.
The virus has the capability of infecting blood cells and mammary tissue of beef and dairy cattle. So how is a bovine virus connected to one of the most vicious human diseases? Now they wanted to find out if this virus can also contribute to breast cancer.
Buehring is confident, however, and acknowledges that this was a very “important first step” that medicine had to make.
The researchers are still unsure of how BLV is transmitted to humans.
“We calculate that 37 percent of all breast cancers are attributable to this cause”, Block said.
She went on to add that “As a result, there has been little incentive for the cattle industry to set up procedures to contain the spread of the virus”. If future research uncovers the role of BLV in the formation of breast cancer, it could change the way we look at breast cancer prevention. He noted that virus in the samples may have come from “unpasteurized milk or undercooked meat, or it could have been transmitted by other humans”.
The most recent dairy study carried out in 2007 – involving over 82% of the entire US dairy herd from the nation’s 17 major dairy-producing states – showed that nearly 84% of operations were positive for BLV, though only 7.5% of all operations had independently confirmed the presence of BLV.
“This odds ratio is higher than any of the frequently publicized risk factors for breast cancer, such as obesity, alcohol consumption and use of post-menopausal hormones”, said Buehring. The research suggests that the probability of a person developing breast cancer is significantly higher if BLV is present. Fortunately, vaccines have been developed for both those viruses and are used to prevent cancers associated with them.