In a seismic revelation shaking the foundations of public health policy, a landmark study analyzing over 8.4 million South Koreans has uncovered stunning associations between COVID-19 vaccination and dramatically elevated risks of multiple deadly cancers within just one year.
Published on September 26, 2025, in the peer-reviewed journal Biomarker Research, the population-based cohort study, drawn from the Korean National Health Insurance database (2021-2023), compared vaccinated vs. unvaccinated individuals using rigorous propensity score matching (PSM) to control for confounders like age, sex, and comorbidities. The study found elevated cancer risks within one year after COVID-19 vaccination in a population-based cohort of over 8.4 million adults. Researchers found vaccinated individuals showed higher diagnosis rates of several cancer types compared to unvaccinated people. The overall risk of being diagnosed with any cancer was about 27% greater in those who received the vaccine. Specifically, risks increased by 53% for lung cancer and 69% for prostate cancer.
Women who received the vaccine had higher chances of developing thyroid and colorectal cancers, while men showed elevated risks for gastric and lung cancers. Older adults experienced the most pronounced increase, but younger adults also faced greater risks of thyroid and breast cancers after vaccination.
The researchers hypothesized that the oncogenic potential of SARS-CoV-2, the virus behind COVID-19, could extend to its vaccines, though real-world evidence had been limited until now. To explore this, they categorized participants into vaccinated and unvaccinated groups, employing multivariable Cox proportional hazards models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). The results were stark: overall cancer risk rose by approximately 27%, with specific elevations including a 69% higher risk for prostate cancer.
The study’s release has sparked a firestorm on social media and among medical professionals. Vaccine skeptics and prominent figures have hailed it as confirmation of long-suspected dangers. Dr. Peter McCullough, a cardiologist known for his criticism of COVID-19 vaccines, shared the findings on X, declaring, “South Korea’s Disturbing Report: Unvaccinated vs. Vaccinated… The vaccinated group showed a 27% higher overall cancer risk, including significant rises in prostate, lung, thyroid, and breast cancers.”
Similarly, British nurse educator Dr. John Campbell dissected the data in a viral video, describing it as “an unmitigated disaster with no one held accountable,” and highlighting specific increases like 53% for lung and 69% for prostate cancer. Investigative journalist Sonia Elijah amplified the alarm on X, posting, “BOMBSHELL: New study in Biomarker Research links COVID shots to 20-69% higher cancer risk (thyroid, gastric, lung, more) in 8M South Koreans.” Another user, @_aussie17, a former pharmaceutical executive, exclaimed, “Shocking Study Alert! A massive South Korean analysis of 8.4 MILLION people found a 35-69% HIGHER risk of cancers like thyroid, stomach, colon, lung, breast & prostate—starting 1 YEAR after COVID vaccines!”
Oncologist Wafik S. El-Deiry also shared the study directly on X, noting its focus on the “oncogenic potential of SARS-CoV-2” and the observed risks, which garnered widespread attention. These voices echo concerns about potential mechanisms, such as vaccine-induced inflammation, disruption of tumor-suppressing pathways, or alterations in the renin-angiotensin-aldosterone system, as speculated in the paper.
An Instagram post from a public health account echoed this, explaining, “A population-based retrospective study from South Korea is being touted as evidence that COVID-19 vaccines may cause cancer, but… [it] shows associations, not causation; fact-checks and methodological reviews have highlighted these problems.” Despite no formal retraction or correction noted on PubMed as of this date, some observers speculate that the journal might issue an expression of concern, given the controversy.
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