About 37% of breast cancer cases may be caused by exposure to bovine leukemia virus.
The incidence of breast cancer continues to increase worldwide. In the United States, this was a 40% increase in incidence at the turn of the century. Currently, the main way to prevent death 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 get breast cancer at all?
“Overall, it is estimated that 20% of all human cancers have an infectious origin.” Bacteria can trigger cancer by turning on cancer genes or by turning off cancer suppressor genes, but they can also contribute to tumor formation by causing chronic inflammation. Currently, cancer-causing bacteria are considered “the most plausible theory for the 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 studied how the mammary tumor virus was found in mice. Scientists transplanted baby mouse pups from mothers with a high rate of breast cancer when the children were from mouse strains with a low rate and found that the incidence of cancer in the pups was similar to their foster mothers’—not their natural mothers’—indicating that it was not genetic. “It occurred to me that people were raised by cows,” said the professor.
Bovine leukemia virus (BLV) was recently identified as a cow virus that causes cancer. At the time, only about 10% of US dairy cows were infected, but now it’s close to half. Initially, 66% of the herds were affected. Then, it was like 80%, based on the testing of their milk to be infected, and 100% of the herds in the big industrial farms. And now, more than 94% of US herds are affected, continuing the historic trend of BLV increasing among US dairy herds.
We have long known that people in countries that consume a lot of milk have a higher rate of breast cancer. But, as you can see below and at 2:32 in my video, Bovine Leukemia Virus as a cause of breast cancerThe connection between milk consumption and breast cancer is not only at the national level.Individual women who are lactose intolerant and consume less milk also appear to have a reduced risk of breast cancer. Milk contains many factors that can contribute to cancer risk, such as saturated fat and the presence of cancer-promoting growth hormones such as IGF-1.
Yes, we know that bovine leukemia virus is present in beef and dairy products. About half of the milk and meat samples tested positive. In fact, you can sample the virus directly from the air on dairy farms, from surfaces, and from the milk itself. Most milk is pasteurized, but many dairy products, such as raw, aged cheese, are not. And who hasn’t eaten a pink-in-the-middle hamburger at some point in their life?
Yes, we have evidence that people are at risk of contracting the virus. Yes, we have evidence that people have been infected with the virus. But it wasn’t until 2015 that we learned that infection rates were much higher in cancerous breast tissue, as you can see below and at 3:30 in mine. video.
As much as 37% of breast cancer cases can be caused by exposure to bovine leukemia virus.
That was enough for me to make a series of videos on the role of the virus in breast cancer and how the meat and dairy industries reacted to the news. What is the latest update? That’s what I’ll cover next.
Doctor’s Note
You may remember that I have discussed before The Role of Bovine Leukemia in Breast Cancer as well as Industry Response to Bovine Leukemia Virus in Breast Cancer.
Stay tuned for the following video: Breast Cancer and Bovine Leukemia Virus in Meat and Milk.
