The Role of Bovine Leukemia Virus in Breast Cancer

Up to 20% of all cancers are linked to infections—particularly viruses—and the list of potentially carcinogenic infectious agents is growing. It could be great if we found a virus that contributed to breast cancer risk, because then, we might have new ways to prevent and treat it. Currently, the dietary link between meat and dairy and breast cancer is considered a saturated fat effect. But, there is a cancer-causing cow virus that infects the mammary gland cells of cows. Infectious virus is then released into the milk supply. And, since most U.S. dairy herds are infected, scientists figured Americans are often exposed to this bovine leukemia virus. But, we didn’t have proof, until 2003—34 years after the virus was first identified.

Early on, our best available tests failed to find antibodies to the virus in human blood. When our immune system is exposed to a virus, it creates antibodies to attack it. No antibodies; no exposure. So, this led to the prevailing opinion that this virus poses no public health hazard. Those tests were state of the art at the time, but extremely insensitive, compared to more modern techniques.

bovine-leukemia-virus-in-breast-cancerSo, researchers decided to re-examine the issue, now that we had better tests. So, they took blood from about 250 people just to answer the question: Do any humans have antibodies to bovine leukemia virus? And 191 of them did; 74%—not that we should be surprised. By then, nearly 90% of American dairy herds were infected. And in the latest national survey, 100% of the big factory farms were infected when you test the milk coming out of those operations.

So, why isn’t there an epidemic of udder cancer out there? Well, see, dairy cattle are hamburgered so young that there’s not a lot of time for them to develop gross tumors. And, that’s how most women may be getting infected. Although pasteurization should knock out the virus, who hasn’t eaten a pink-in-the-middle burger at some point in their life?

The bottom line is that the long-held assumption that bovine leukemia virus is not a public health hazard is no longer tenable. This whole field of investigation needs to be reopened, with the next step determining whether humans are actively, actually infected. The presence of antibodies is generally interpreted as an indicator of past or present infection. But, theoretically, maybe we just made antibodies to dead virus we ate—virus that had been killed by cooking, or pasteurization. Just because three-quarters of us have been exposed doesn’t mean we were actively infected with the virus.

To prove that, we’d actually have to find the retrovirus actively stitched into our own DNA. Well look, millions of women have gotten breast surgery. Why not just look at that tissue? Researchers did, and, in 2014, published their findings in the CDC’s Emerging Infectious Diseases journal. And, 44% of samples tested positive—proving for the first time that humans can be infected with bovine leukemia virus.

The final step then, is to determine if the virus is actually contributing to disease. In other words, are the bovine leukemia viruses we’re finding in breast tissue cancer-causing, or just harmless passengers? One way to figure that out is to see if the virus is more often present in those with breast cancer. But no one had ever looked for the virus in breast tissue from cancer victims, until now. The presence of bovine leukemia virus DNA in breast tissues was strongly associated with diagnosed and confirmed breast cancer. As many as 37% of breast cancer cases may be attributable to BLV exposure. As many as 37% of human breast cancer cases may be attributable to exposure to bovine leukemia virus.

Doctor’s Note

For some historical background leading up to these shocking findings, see my last video, Is Bovine Leukemia Virus in Milk Infectious?

I couldn’t wait to read the meat and dairy industry journals to see how they’d try to spin this. Find out what I found out—in my next and final video in this series, Industry Response to Bovine Leukemia Virus in Breast Cancer.

In health,
Michael Greger, M.D.

Michael Greger, M.D., is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous “meat defamation” trial. Currently Dr. Greger proudly serves as the Director of Public Health and Animal Agriculture at the Humane Society of the United

Why are women at a higher risk of leukemia after breast cancer treatment?

leukemia after breast cancer treatmentResearchers have been trying to determine ways to prevent the complications in the breast cancer survivors to reduce the occurrence of a relapse. The breast cancer treatments that include radiation therapy and chemotherapy target the malignant cells in the breast tissues and destroy them.

However, these treatments also affect the healthy cells, which results in an increase in the risk of leukemia in the future, the researchers said. They are conducting studies to determine the factors that may cause an increased risk of leukemia after breast cancer treatment.

The possible factors that are believed to contribute to the risk of secondary malignancy are the family history of cancer and an inherited gene mutation.

The research involved a follow-up of 88 breast cancer survivors who were treated for breast cancer and developed leukemia at a later stage. It was found that the women had a family history of cancer, which suggested a genetic susceptibility to develop cancer like leukemia.

About 20 percent of the women in this study group had an inherited gene mutation, which can increase the risk of breast cancer.

“This is expected to enable the scientists in determining how these genes affect or modify the breast cancer treatment-related leukemia risk. It will also help to understand whether any specific treatment causes a higher risk based on the inherited genetic make-up of a woman,” said Dr. Jane Churpek, the study leader from the University of Chicago.

This will help the oncologists to have a patient-specific conversation about the potential risks of radiation and chemotherapy treatments for breast cancer.

It may be difficult to determine the exact role of breast cancer treatment in the development of leukemia. Hence, it is important that the breast cancer patients are uniquely positioned so that the true frequency and the causative factors of subsequent leukemia can be ascertained.

American Society of Clinical Oncology and the American Cancer Society have issued guidelines for improving the survival rates of breast cancer patients. The breast cancer survivors are advised to undergo routine physical exams and mammograms to check for any new tumor.  They do not need additional lab tests or imaging unless there are significant symptoms suggesting that a malignancy may have returned.

The guidelines include recommendations in five key areas, which include:

  • Regular surveillance for the recurrence of malignancy by physical examination and the patient’s cancer history
  • Regular mammographic screening
  • Management and assessment of the psychosocial and long-term physical impact of breast cancer treatment
  • Care coordination and practical implications
  • Promotion of a healthy lifestyle

With regular follow-up and monitoring, the occurrence of complications following breast cancer treatment is expected to decline. This will increase the life expectancy of breast cancer survivors and also improve their quality of life.

1. Leukemia Risk After Breast Cancer Treatment
2. ASCO and ACS Issue Guideline on Breast Cancer Survivor Care
3. Organizations issue joint guidelines for breast cancer survivors

Featured Photo:

Dr. Adem GunesDr. Adem Gunes has built the world’s largest database of scientifically tested natural substances with proven effects in cancer treatments. In 2009, he was appointed as the Chief Physician of ProLife Clinic in Innsbruck, Austria, and played a key role in the establishment of the research laboratory. He is also the co-founder of the first Austrian hyperthermia center. Now, Dr. Adem works closely with cancer patients from around the world (including Germany, Thailand, Dubai) to recommend them a complementary cancer clinic or to create a personalized care plan for patients to follow at home.


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