Hong Hin Kim, Min-Ho Kim, Myeong Geun Choi, Eun Mi Chun, September 2025
This large-scale population based study was done in Seoul, South Korea with data from 2021 through 2023 involving 8.4 million people.
Overall risk of cancer was 27% higher in vaccinated vs. unvaccinated (HR 1.27, 95% CI 1.21-1.33).
Lung cancer risk increased by 53% (HR 1.53, 95% CI 1.25-1.87).
Prostate cancer risk increased by 69% (HR 1.69, 95% CI 1.35-2.11).
Thyroid cancer risk increased by 35% (HR 1.35, 95% CI 1.21-1.52).
Stomach cancer risk increased by 34% (HR 1.34, 95% CI 1.13-1.58).
Colorectal cancer risk increased by 28% (HR 1.28, 95% CI 1.12-1.47).
Breast cancer risk increased by 20% (HR 1.20, 95% CI 1.07-1.34).
Vaccine Platform
cDNA vaccines (eg. AstraZenica) increased overall risk of cancer by 47% (HR 1.47, 95% CI 1.39-1.56).
mRNA vaccines (eg. Pfizer/Moderna) increased overall risk of cancer by 20% (HR 1.20, 95% CI 1.14-1.26).
Mixed schedules increased overall risk of cancer by 34% (HR 1.34, 95% CI 1.21-1.48).
Booster Dose Risk
Booster doses increased the risk of stomach cancer by 23% (HR 1.23, p=0.041).
Booster doses increased the risk of pancreatic cancer by 125% (HR 2.25, p<0.001).
Overall Trends
All demographic groups, including young adults, had a higher incidence of cancer. The mean age of individuals in this study was 44yo.
Men had a higher risk for stomach and lung cancers.
Women had a higher risk for thyroid and colorectal cancers.
https://pubmed.ncbi.nlm.nih.gov/41013858
https://biomarkerres.biomedcentral.com/articles/10.1186/s40364-025-00831-w