Dairy Industry Responds to Bovine Leukemia Virus in Breast Cancer

What was the response to the revelation that as many as 37 percent of breast cancer cases may be attributed to exposure to bovine leukemia virus (BLV), a cancer-causing cow virus found in the milk of nearly every dairy herd in the United States? I discuss this issue in my video Industry Response to Bovine Leukemia Virus in Breast Cancer. The industry pointed out that some women without breast cancer harbored the virus, too. Indeed, BLV was found in the tissues of 29 percent of women who didn’t have breast cancer, a finding the researchers replied “is not surprising considering the long latency period of breast cancer…” In other words, they may not have breast cancer yet.

It can take decades before a breast tumor can be picked up on mammography. So, even though people may be harboring this virus in their breast and feeling perfectly fine, the cancer may still be on its way. That’s how other cancer-causing deltaretroviruses appear to work. These viruses can make proteins that interfere with our DNA repair mechanisms. Infected cells are then more susceptible to carcinogens and slowly accumulate mutations over time. “Therefore, evidence of BLV in normal breast tissues prior to premalignant and malignant changes would be expected.” This pattern is what we see with cervical cancer, “in which the causative virus (HPV) is found not only in the malignant [cancerous] tissue, but also in premalignant dysplastic areas [the precancerous tissue] and in normal tissue adjacent to the malignant tumor.”

If BLV, a retrovirus, is really causing thousands of cases of breast cancer every year, wouldn’t some of the anti-retroviral therapies like some of the AIDS drugs be able to counter it? Perhaps, but it’s best not to get infected in the first place.

However, the agriculture industry appeared to be more concerned about consumer confidence in U.S. dairy than consumer cancer. Indeed, the “U.S. dairy industry face[d] a brewing public-relations brouhaha,” and it became “concerned about the possibility of eventual mandatory control of these diseases in dairy cattle along with public perception and an impact on the consumption of dairy products.” What would control look like? BLV is a blood-borne virus, but how is it spread? Is Bessie sharing dirty needles? In a sense, yes: “[B]lood (and BLV virus) is readily spread from animal to animal with blood contaminated needles and/or syringes, obstetrical sleeves, saw or gouge dehorners, tattoo pliers, ear taggers, hoof knives, nose tongs,” and other instruments that aren’t disinfected between animals. So, for example, when farmers are gouging or sawing at the cows’ heads during dehorning, “they are likely to drive blood into the next animal during the subsequent dehorning process.” Or, when they’re sticking their arms into cows’ rectums for artificial insemination, it’s not uncommon for there to be rectal bleeding—then they just go from one cow to the next.

More than 20 countries have successfully eradicated BLV from their herds by changing their practices, whereas it remains an epidemic in the United States in part because we’re not cleaning and disinfecting blood-contaminated equipment for things like “supernumerary teat removal,” which is done because “the presence of extra teats detracts from the beauty of the cow.” Supernumerary teats are removed by pulling them from the udder and cutting them off with a pair of scissors. Those scissors had better be clean—otherwise they could spread BLV from calf to calf and ultimately to someone’s breakfast, lunch, or dinner. Of course, we could just not slice off their teats at all, but then how would we “improve udder appearance?”


Up to 37 percent of breast cancer cases are attributable to exposure to bovine leukemia virus? See my video The Role of Bovine Leukemia Virus in Breast Cancer and its prequel, Is Bovine Leukemia Virus in Milk Infectious?.

The meat and dairy industries’ intransigence in the face of a human health threat reminds me of the antibiotics and steroids issues—continuing to place the public at risk to save a few bucks. See, for example, Antibiotics: Agribusinesses’ Pound of Flesh and Zeranol Use in Meat and Breast Cancer.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

The Vitamin C Cancer Study that Started It All

In 1975, a remarkable case was reported of a 42-year-old man suffering from a malignant form of non-Hodgkin’s lymphoma who experienced a dramatic regression of the cancer after being given large doses of vitamin C intravenously, as I discuss in my video Intravenous Vitamin C for Terminal Cancer Patients. He seemed cured, so they stopped the vitamin C. The cancer came surging back. They restarted the vitamin C and apparently induced a second complete remission. Sometimes cancer does just spontaneously regress—it’s rare, but not unheard of. So, one could argue that the first remission was spontaneous, and it was just a coincidence that it happened when they started the vitamin C. However, given the trajectory the cancer was on, followed by the rapid remission, followed by the relapse when the vitamin C was stopped, followed by a second remission once restarted, the case strongly suggests that the vitamin C had something to do with the cancer’s remission.

Now, multiple spontaneous regressions do exist. There was a recent case, for example, of a woman with cervical cancer who appeared to be cured with radiation and chemo. Her cancer came back and she refused further treatment. Yet, the tumors disappeared on their own, then came back, then disappeared, then came back, then disappeared, then came back, and then disappeared for a fourth spontaneous remission—and all that was with no apparent treatment at all. So, it’s possible this vitamin-C case is just a crazy, coincidental fluke, and the vitamin C didn’t help at all. You never know until you put it to the test.

Researchers enlisted the help of Linus Pauling, who they considered the greatest chemist of the 20th century and who was known to be interested in vitamin C. If he couldn’t get funding, nobody could get funding. And he couldn’t get funding. They went to the National Cancer Institute with promising data on the first 40 cancer patients they had treated with vitamin C and asked that the institute carry out or fund a randomized double-blind trial. In this type of trial, they would take a group of incurable cancer patients for whom medicine has nothing more to offer, randomly split them into two groups, and infuse one group with vitamin C and the other group with something like saline, basically water, and then see who lives the longest. Neither the patients nor the doctors would know who got the vitamin C and who got the saline to eliminate bias and placebo effects. The researchers and Pauling went back year after year after year asking for grants to study it themselves if the National Cancer Institute wasn’t going to do it, and they got rejected year after year after year. So, they scraped up whatever funds they could find and did their best with what they had. They published their findings in 1976.

The researchers didn’t have a controlled trial, but, by that point, they had treated a hundred terminal cancer patients with vitamin C. So, they compared their progress to that of a thousand similar patients who did not get vitamin C. For each patient treated with vitamin C, the researchers found ten patients about the same age and with the same kind of cancer who had been treated at the same hospital but who had not received the vitamin C infusions. What did they find? In patients with terminal breast cancer, within a hundred days, more than 80 percent of the women in the control group were dead. (Remember, these were all terminal cancer patients.) However, in the vitamin C group, half were still alive nearly a year later. The vitamin-C group had women with terminal breast cancer still alive 2,270 days later and counting.

The control groups for all the different cancers studied did predictably poorly, with the vast majority dead within 100 to 200 days, while the vitamin C-treated patients appeared to do substantially better. All in all, the average survival time was four times as great for the vitamin C subjects—more than 200 days compared to only 50 days for the control patients. The results, the researchers concluded, “clearly indicate that this simple and safe form of medication is of definite value in the treatment of patients with advanced cancer.” So, what happened after the study was published back in 1976?

Critics understandably attacked the study for using after-the-fact controls. One can see how this could introduce bias. If researchers consciously or unconsciously chose control group patients who were sicker than the treatment group patients, the control group patients would die sooner than the treatment group patients, but it would have nothing to do with the treatment; the control group folks may have just started out in a worse place. Indeed, there is evidence that is what happened: A full 20 percent of the control group died within a few days after being declared terminal compared to none in the treatment group, which really does seem fishy. Nevertheless, the trial was successful in finally convincing the National Cancer Institute to fund randomized controlled trials—performed by the prestigious Mayo Clinic, no less. What did they find? Find out in Vitamin C Supplements for Terminal Cancer Patients and The Role of Vitamin C in the Treatment of Terminal Cancer.


I have tons of videos on cancer, but here’s a sampling:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: