A newly published systematic review examining global research on COVID-19, vaccination and cancer has identified what its authors describe as potential “safety signals” that warrant further scientific investigation, while stopping short of concluding that COVID-19 vaccines cause cancer.
The review, published last week in the peer-reviewed journal Oncotarget, analysed 69 studies and reports conducted between January 2020 and October 2025.
According to the authors, the body of literature reviewed points to recurring patterns involving certain blood and solid cancers following COVID-19 vaccination or SARS-CoV-2 infection.
Among the cancer types most frequently cited in the studies were leukemia, lymphoma, breast cancer and lung cancer.
About 43 per cent of the reviewed publications reported lymphoid malignancies, including both leukemias and lymphomas, while 41 per cent identified associations involving solid tumours such as melanoma, breast and lung cancers, sarcomas and organ-specific cancers including pancreatic cancer.
The authors noted that the interval between vaccination and the reported onset or recurrence of cancer varied widely, ranging from as little as two to four weeks to eight months or more after vaccination or booster doses.
Several studies highlighted what the review described as “unusually rapid progression, recurrence, or reactivation” of pre-existing cancers, as well as atypical clinical presentations.
Some reports also documented tumour development or recurrence close to vaccine injection sites, and the reactivation of previously dormant tumours.
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The review outlined proposed biological mechanisms that could potentially explain such observations, including the role of the SARS-CoV-2 spike protein and reports of DNA contamination identified in some vaccine types. The authors stressed, however, that these mechanisms remain hypothetical and unproven.
Wafik El-Deiry, M.D., Ph.D., a senior author of the review, described the paper as the most comprehensive effort to date summarising global literature on COVID-19 vaccines, infection and cancer outcomes.
“This is the first most comprehensive presentation summarizing the world’s literature on the subject matter of COVID vaccines, COVID infection and cancer,” El-Deiry said, adding that some of the recurring findings “look like a smoking gun” and justify deeper investigation.
Importantly, the authors emphasised that the review does not conclude that COVID-19 vaccines cause cancer. Instead, it argues that consistent patterns observed across different cancer types and countries should not be dismissed without further study.
Commenting on the findings, Karl Jablonowski, Ph.D., a senior research scientist with Children’s Health Defense, said the review may represent “the tip of a very damaging iceberg,” arguing that long-term oncogenic safety was not adequately assessed before mass vaccination campaigns.
His comments reflect a critical perspective that is not universally shared within the scientific community.
The review also referenced several large-scale observational studies. These included a two-year study of 8.4 million people in South Korea, which reported statistically significant associations between COVID-19 vaccination and six cancer types — breast, colorectal, gastric, lung, prostate and thyroid — alongside a reported 27 per cent higher overall cancer risk.
Another cited study, involving nearly 300,000 Italians, found moderately higher cancer-related hospitalisations among vaccinated individuals, particularly for bladder, breast and colorectal cancers.
Independent experts not involved in the review have previously cautioned that observational associations do not prove causation and that factors such as delayed diagnoses during the pandemic, improved cancer detection, and population-wide stressors may also influence cancer trends.