Gertrude Buehring, the lead author of this study & a virology expert from UC Berkeley along with her fellow researchers all believe that simple contact with this bovine virus can cause breast cancer.
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They identified BLV in 59% of samples from breast cancer patients, compared with 29% in the samples from those without breast cancer.
According to Gladys Block, a UC Berkeley professor emerita of nutritional epidemiology who co-authored the study, the odds of having breast cancer were roughly three times greater in subjects in which BLV was present.
Last year, Buehring and her team published a study confirming the presence of bovine leukemia virus in the mammary epithelial cells of human breast tissue, where breast cancer originates.
Evidence of exposure to bovine leukaemia virus (BLV) has been found in human breast cancer samples.
Buehring is confident, however, and acknowledges that this was a very “important first step” that medicine had to make.
“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”.
As explained in a concurrent press release, a 2014 study published in Emerging Infectious Diseases confirmed the presence of BLV in humans, though it is now unknown how the virus passes between species.
The study analyzed breast tissue from 239 women. But DNA tests in the 1990s started to challenge the belief that humans were immune to the virus.
The research team could not find any definitive proof of how bovine leukemia infects breast tissue, however this does not mean that they don’t have any theories.
Breast cancer is the most common cancer in women, regardless of race or ethnicity, reported the Centers for Disease Control and Prevention.
“Studies done in the 1970s failed to detect evidence of human infection with BLV”, said Buehring.
A 2007 U.S. Department of Agriculture survey of bulk milk tanks found that 100 percent of dairy operations with large herds of 500 or more cows tested positive for BLV antibodies. Vaccines, which have been developed for both these viruses, are routinely used to prevent the cancers associated with them.
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She also added that “As a result, there has been little incentive for the cattle industry to set up procedures to contain the spread of the virus”. This is the first suggestion of a possible link between infection with a leukaemia virus prevalent in cows and breast cancer in humans. According to Buerhing, this could revolutionize the way scientists approach the disease by expanding more on preventive measures rather than searching for a cure.
