A recently published scientific review has drawn attention to reports of cancer diagnoses and disease progression observed after Covid-19 vaccination, prompting renewed discussion within the scientific community about the interpretation of post-vaccination health events. The review, released earlier this year in the peer-reviewed journal Oncotarget, examined reported cases associated primarily with mRNA vaccines produced by Pfizer-BioNTech and Moderna, which have been widely administered across numerous countries.
The authors analysed 69 scientific reports published between January 2020 and October 2025, documenting instances of newly diagnosed cancers, cancer recurrence or unusually rapid disease progression occurring after Covid-19 vaccination or SARS-CoV-2 infection. Among these publications were 66 clinical case reports and series, two large retrospective population-based studies and one longitudinal analysis comparing pre-pandemic and post-pandemic periods.
Scope of the Reported Cases
Across the reviewed literature, a total of 333 patients from 27 countries were described. The reported malignancies included haematological cancers, such as lymphomas and leukaemias, as well as solid tumours, including breast, lung, pancreatic and skin cancers, glioblastoma and virus-associated malignancies.
According to the review, most of the reported cases occurred following vaccination rather than infection. Of these, 56% were temporally associated with the Pfizer-BioNTech vaccine (BNT162b2) and 25% with the Moderna vaccine (mRNA-1273), a distribution that the authors note largely reflects the global predominance of these vaccines during mass immunisation campaigns.
Findings from Population-Level Studies
In addition to individual case reports, the review discussed two large observational studies conducted in Italy and South Korea. The Italian study followed approximately 300,000 individuals, while the South Korean analysis included data from around 8.4 million people. Both studies identified statistical associations between Covid-19 vaccination and an increased incidence of, or hospitalisation for, certain cancers.
However, the authors emphasised that these findings are subject to important methodological limitations, including potential confounding factors, detection bias and differences in healthcare utilisation during the pandemic period. They stressed that such associations do not establish causality.
Possible Biological Explanations Under Discussion
The review explored several hypothetical biological mechanisms that could, in theory, influence cancer behaviour in certain contexts. These include transient immune responses, short-term inflammatory processes and temporary alterations in immune surveillance that might affect pre-existing or dormant tumours.
Nevertheless, the authors underscored that these mechanisms remain speculative. They reiterated that demonstrating a causal link between vaccination, viral infection and cancer development requires a far higher level of evidence than temporal coincidence alone.
Call for Further Research
The authors concluded that significant knowledge gaps remain in understanding the long-term interactions between Covid-19 vaccination, infection and cancer biology. They called for extended follow-up studies, integrating clinical observations with epidemiological data and molecular research, to clarify whether — and under what conditions — vaccination or infection might be linked to cancer development or progression.
Importantly, the review does not establish a causal relationship, but rather highlights the need for continued scientific scrutiny. In the context of global public health, the authors stress that careful interpretation of emerging data is essential to avoid misrepresentation of findings while ensuring that potential risks, if any, are rigorously investigated.