Study: Increased Cancer Risk 1 Year after COVID-19 Vaccine

Simian Practicalist
Oct 4
2 min read

A correspondence by Kim Hong-jin et al titled “1-year risks of cancers associated with COVID-19 vaccination: a large population-based cohort study in South Korea” posted on 26 September 2025 supports what has been hypothesized by some doctors since the rollout of the so-called vaccine.

COVID-19 isn’t the only virus with “oncogenic potential”. That’s not new. However, since the vaccine shares the same structures (such as the spike protein), it is reasonable that the vaccine can cause cancer.

The study included 8,407,849 individuals in South Korea between 2021 and 2023. At least two-thirds of the vaccinated received the Pfizer injections.

There is a slight increase in the overall risk of cancer. This is more pronounced as more time passes, with a higher cumulative incidence for vaccinated females and those aged 65 years and older.

Not all cancer types have increased risk but 6 in particular are significant:

Thyroid – HR: 1.35, 95% CI: 1.21–1.51
Gastric – HR: 1.34, 95% CI: 1.13–1.58
Colorectal – HR: 1.28, 95% CI: 1.12–1.47
Lung – HR: 1.533, 95% CI: 1.25–1.87
Breast – HR: 1.20, 95% CI: 1.07–1.34
Prostate – HR: 1.69, 95% CI: 1.35–2.11

In addition, the odds for brain cancer, cervical cancer, ovarian cancer, Hodgkin lymphoma and non-Hodgkin lymphoma don’t look good either.

As for vaccine type,

…cDNA vaccines were associated with the increased risks of thyroid, gastric, colorectal, lung, and prostate cancers; mRNA vaccines were linked to the increased risks of thyroid, colorectal, lung, and breast cancers; and heterologous vaccination was related to the increased risks of thyroid and breast cancers.

As for boosters, there is a significant increase in risks for gastric cancer and pancreatic cancer whilst there is a decrease in leukemia. If one is less tight with the P-values, then there is an increased risk in cervical cancer, prostate cancer and Hodgkin lymphoma whilst there is a decrease in Myeloma.