Concerns about a potential link between COVID-19 vaccines and cancer have been circulating since the vaccines became widely available, prompting close scrutiny from the scientific community. Even as reports have emerged suggesting a possible association, experts emphasize the critical demand to differentiate between coincidental timing and a true causal relationship.
A systematic review of scientific literature, published in the National Library of Medicine (PubMed) and covering data from January 2020 through October 2025, analyzed 69 publications documenting cancer cases appearing after COVID-19 vaccination or SARS-CoV-2 infection. The study included reports from 333 patients across 27 countries, as well as large-scale investigations conducted in Italy, South Korea, and the United States.
Researchers identified several notable findings. The most commonly reported cancers included hematologic malignancies – such as lymphomas and leukemias – as well as solid tumors like breast cancer, lung cancer, melanoma, and sarcoma, and virus-associated cancers.
Recurring patterns observed in the reviewed cases included unusually rapid disease progression, recurrence or reactivation of previously controlled illnesses, and atypical histopathological findings, including tumors near the injection site or in regional lymph nodes. The study highlights the importance of ongoing safety signal detection as vaccine programs continue globally.
However, the study concluded that these findings represent an early phase of safety signal detection, and do not prove that the vaccine causes cancer.
A cohort analysis conducted in the province of Pescara, Italy, following nearly 300,000 individuals for 30 months, yielded complex data. Vaccinated individuals showed a significant reduction in all-cause mortality.
Regarding cancer specifically, the study observed a slightly higher probability of hospitalization for the disease in the vaccinated group, particularly among those without prior infection. However, this association disappeared or reversed when researchers applied a 12-month latency period between vaccination and hospitalization, suggesting other factors may be influencing the initial data.
Evidence of Benefits for Cancer Patients
Contrary to concerns about potential risks, other studies published in 2025 have highlighted the protective benefits of COVID-19 vaccines for individuals already living with cancer.
Research published in Nature showed that receiving an mRNA vaccine shortly before initiating therapies with “immune checkpoint inhibitors” was associated with nearly double the probability of overall survival in patients with melanoma and lung cancer. This is likely due to the vaccine’s potent immunomodulatory effects.
Cancer patients who received booster doses experienced between a 29% and 30% reduction in hospitalizations and ICU admissions due to COVID-19.
Investigations in JCO Oncology Advances indicated that vaccinated patients diagnosed with COVID-19 had a 6-month survival rate of 90%, compared to 82% for those who were unvaccinated.
The scientific community stresses that, in oncology, causality cannot be determined by a single observation. While statistical correlations exist and should be investigated through more robust genomic and epidemiological studies, there is currently insufficient evidence to assert that vaccines cause cancer. Currently, vaccines remain considered safe and effective for the general population and for those with cancer, offering critical protection against severe complications from the virus.
