Paper does not prove Pfizer mRNA vaccine causes 'turbo cancer'

"In a new Belgian study by Sander Eens et al. they injected 14 mice with 2 Pfizer COVID-19 mRNA vaccines. 2 days after 2nd Pfizer dose, 1/14 mice (7%) died suddenly, had turbo cancer with lymphoma infiltration of many organs: liver, kidneys, spleen, lungs & intestines," claims a July 7, 2023 tweet from an account linked to the widely debunked film "Died Suddenly."

Similar claims can be found on Instagram and circulating in French.

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Screenshot of a tweet taken July 18, 2023

The posts are the latest on social media claiming -- without scientific evidence -- that Covid-19 vaccines lead to "turbo cancer," a term suggesting fast-growing tumors which has been coined by vaccine skeptics.

The US National Cancer Institute says on its website: "There is no evidence that Covid-19 vaccines cause cancer, lead to recurrence, or lead to disease progression."

The Belgian paper being shared on social media (archived here) is titled: "B-cell lymphoblastic lymphoma following intravenous BNT162b2 mRNA booster in a BALB/c mouse: A case report," and was published in the open-access journal Frontiers in Oncology (archived here) in May 2023.

The journal has been classified as "predatory" by some researchers and can be found on Beal's list (archived here), which includes publications found willing to take papers in exchange for payment.

The experiment looked at whether the Pfizer vaccine causes lymphoma by giving 14 mice two doses of the mRNA shot. Two days following the second dose, one of the mice "suffered spontaneous death" and showed lymphoma in several organs.

The tweet claims: "The turbo cancer mouse had shown no clinical signs of illness before sudden death," but this is not what the paper reported.

"When we look at their results depicted in Figure 4, where they compare the growth curve of the animals -- a way to measure whether the animals are healthy or not -- we see that the mouse they injected and who has developed tumors is different from other animals," Mathieu Gabut, a researcher at the Lyon Cancer Research Center (CRCL), said on July 13.

"It loses weight while the others gain it. But the change in body mass occurs even before the first of the two injections, between weeks 5 and 6," he said.

This is seen in the graph below -- the red line shows the growth curve of the deceased mouse, which started to lose weight before being vaccinated.

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Screenshot taken from the National Library of Medicine on July 17, 2023

Additional flaws

The paper's abstract does not claim to have proven the vaccine caused the cancer. The authors say their case study "adds to previous clinical reports on malignant lymphoma development following novel mRNA Covid-19 vaccination, although a demonstration of direct causality remains difficult."

While case studies can inform, Bruno Quesnel (archived here) director of research and innovation at France's National Cancer Institute, said scientists focus on whether outcomes have been observed repeatedly.

Asked about the Belgian paper, Quesnel told AFP: "It is impossible to establish the slightest cause and effect link in an experimental model like this. To do this, the experiment would have had to be repeated by carrying it out in several cohorts of mice."

He said that any animal can spontaneously develop tumors. "The mice observed in the laboratory are no exception to the rule."

Pierre Saintigny (archived here), an oncologist and researcher at the Léon Bérard cancer center agreed, pointing to two studies (here and here) about tumors in mice. "Mice spontaneously develop lymphomas...the authors do not even discuss it," he said on July 13.

Other flaws in the report were raised by David Gorski, professor of oncology at Wayne State University in the US state of Michigan.

He called into question why the mice were given the vaccine through a tail vein, rather than intramuscularly as it is given to humans, and found the dosage administered to the mice to be far greater than what humans receive.

In a blog post (archived here) he said: "The design was so artificial with its intravenous dosage of a vaccine not intended to be administered intravenously plus its use of such a massive dose, that, no matter what the results of the study, they would not be applicable to humans."

Vaccines recommended

Health organizations in the US and Canada recommend Covid-19 vaccines to cancer patients as large studies have demonstrated that such individuals are at high risk for complications from Covid-19.

More than 83 percent of Canada's population has received at least one dose of a Covid-19 vaccine. Health Canada monitors adverse events following vaccination, and no safety signals related to cancer have been identified.

More of AFP's reporting on vaccine misinformation is available here.