New Study Warns Repeated COVID-19 Vaccination Accelerates Death in Pancreatic Cancer Patients
Nikhil Prasad Fact checked by:Thailand Medical News Team Apr 20, 2025 10 hours, 2 minutes ago
Medical News: A startling new study out of Japan raises alarm over the potential long-term consequences of repeated COVID-19 mRNA vaccinations in cancer patients
A group of researchers from the Miyagi Cancer Center in Natori, Japan, has revealed concerning evidence that repeated COVID-19 mRNA vaccinations—specifically three or more doses—may be associated with significantly poorer outcomes in patients diagnosed with pancreatic cancer. This
Medical News report is based on a retrospective analysis conducted over a five-year period and draws attention to a potential link between the vaccines and suppressed anti-cancer immunity.
The study was conducted by researchers from three departments within the Miyagi Cancer Center: the Department of Gastroenterology, the Division of Cancer Stem Cell at the Research Institute, and the Department of Pathology. Led by Dr. Makoto Abue and colleagues, the team analyzed clinical data from 272 patients diagnosed with pancreatic cancer between 2018 and 2023. Their findings, though preliminary, are compelling and call for further investigation.
How the Study Was Conducted
The researchers divided the patients into several groups based on their COVID-19 vaccination history. They compared outcomes in those who had received up to two vaccine doses with those who had received three or more. They also analyzed blood samples to measure levels of total IgG4 and spike-specific IgG4 antibodies—both of which increase with repeated vaccinations and are known to modulate immune responses.
The team utilized Kaplan–Meier survival analyses, immunohistochemistry on tumor samples to identify regulatory immune cells, and advanced statistical methods such as propensity score matching to ensure the validity of their findings. They also examined key prognostic markers like the neutrophil-to-lymphocyte ratio (NLR), modified Glasgow prognostic score (mGPS), and Prognostic Nutritional Index (PNI).
Key Findings from the Study
The central discovery was striking: patients who had received three or more doses of the COVID-19 mRNA vaccine had significantly shorter overall survival times compared to those with fewer doses. Specifically:
-Median survival dropped to 10.3 months in the heavily vaccinated group versus 14.9 months in those with two or fewer doses.
-Serum IgG4 levels were notably elevated in patients with three or more vaccinations.
-Patients with high IgG4 levels (above 48 mg/dL) had much worse outcomes, with survival time plunging to a median of 10.3 months compared to 20.8 months in those with lower levels.
-Tissue analysis revealed that Foxp3-positive regulatory T cells—a type of immune cell known to suppress anti-tumor activity—were more abundant in patients with higher IgG4 levels and in those with more vaccine doses.
-Interestingly, the study also confirmed a direct correlation between spike-specific IgG4 and total IgG4 levels, strongly indicating that the increase in IgG4 was linked to repeated exposure to the spike protein via vaccination.
Why IgG4 Matters in Cancer
IgG4 is a type of antibody that behaves differently from other immune molecules. While most antibodies help the body fight infections and cancer, IgG4 tends to dampen immune
responses. Normally, this function helps prevent excessive inflammation, but in the context of cancer, it could be dangerous.
Repeated exposure to the same antigen—like the spike protein found in COVID-19 vaccines—can cause a class-switch in B cells to produce IgG4 instead of other more inflammatory types like IgG1. The presence of IgG4 has been previously linked to immune evasion in cancers such as gastric, esophageal, and bile duct cancers. In this study, its association with poor pancreatic cancer outcomes adds another layer of concern.
Furthermore, elevated IgG4 can suppress critical immune functions like antibody-dependent cellular cytotoxicity (ADCC), which is essential for killing cancer cells. This creates a more favorable environment for tumor growth and may explain why vaccinated patients fared worse in this cohort.
Other Immunological Findings
The researchers also noted that patients who had received more vaccine doses showed higher levels of regulatory T cells in their tumors. These cells, marked by the Foxp3 protein, are known to inhibit effective anti-cancer immunity. This aligns with previous findings that mRNA vaccines may increase Treg activity, potentially blunting the immune system’s ability to fight off tumors.
Additionally, patients in the heavily vaccinated group had higher neutrophil-to-lymphocyte ratios and lower PNI scores—both markers of worse prognosis. These findings suggest that repeated vaccination might not only influence antibody production but also alter broader aspects of immune health.
Potential Implications and Limitations
The researchers stress that their study was observational and cannot prove causation. However, the strong correlations, particularly when adjusted for confounding factors such as cancer stage, surgery, and chemotherapy, make the results difficult to ignore.
They caution that these findings should not be taken as a wholesale indictment of COVID-19 vaccines, which have saved millions of lives globally. However, they argue that specific patient populations—like those with pancreatic cancer—may require more nuanced vaccination strategies, especially when considering booster doses.
Other limitations include the single-center nature of the study and the relatively small sample size of patients who had both IgG4 data and full vaccination histories. Nonetheless, this early data may be enough to warrant broader investigations and may influence future guidelines for immunocompromised or cancer-diagnosed individuals.
What Comes Next
The team from Miyagi Cancer Center recommends further studies on a larger scale and inclusion of diverse populations to determine whether these findings hold true elsewhere. They also suggest that monitoring IgG4 levels and Treg activity might be helpful in managing pancreatic cancer patients who have received multiple vaccine doses.
In the future, it may be possible to develop predictive biomarkers that help doctors decide whether additional vaccine doses are safe or potentially harmful for cancer patients. Tailoring vaccine protocols in such cases could maximize protection against COVID-19 while minimizing risks to cancer prognosis.
Conclusion
This groundbreaking study raises urgent questions about the long-term effects of repeated mRNA COVID-19 vaccinations in vulnerable patient populations. The findings suggest that three or more vaccine doses may worsen survival outcomes in pancreatic cancer patients, possibly due to elevated IgG4 levels and increased regulatory T cell infiltration, both of which can suppress the body’s natural defenses against tumors.
The study also sheds light on the complex relationship between vaccines, the immune system, and cancer biology. While vaccination remains a vital public health tool, this research underscores the need for caution, especially in cases involving immunocompromised individuals.
Future clinical decisions regarding booster shots in cancer patients may need to consider individual immune profiles and biomarkers like IgG4 to avoid unintended harm. As science continues to unravel the intricate dance between immunity and cancer, studies like this one pave the way for more personalized and informed medical care.
The study findings were published on a preprint server and are currently being reviewed.
https://www.preprints.org/manuscript/202504.1167/v1
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