SARS-CoV2 and Anti-COVID-19 mRNA Vaccines: Is There a Plausible Mechanistic Link with Cancer?

To contrast the COVID-19 pandemic brought by the corona virus SARS-CoV-2, two mRNA-based anti-COVID-19 vaccines (by Pfizer-BioNTech and Moderna) were rela-tively soon made available and deployed worldwide based on an emergency approval. Being considered vulnerable and at risk of infection, cancer patients have been priori-tized for COVID-19 vaccination and vaccinated repeatedly because of the short-time protection provided by these vaccines. During the pandemic, because of the large number of infected patients requiring assistance, many hospitals opted for giving pri-ority to these patients while postponing the specialist treatment for other pathologies, including cancer. Recently, a surge in the incidence and rapid progression of cancers has been observed in many countries, which could (at least partially) represent those cancers undiagnosed or untreated during the pandemic. It has also been suggested that the SARS-CoV-2 itself or even the anti-COVID-19 mRNA vaccines could have contrib-uted to the recurrence and worse clinical outcome in cancer patients, given the high incidence of COVID-19 in hospitalized patients and that these patients have been vac-cinated with priority several times and in a short period. Although it appears ex-tremely unlikely that SARS-CoV-2 and anti-COVID-19 mRNA vaccines elicit genotoxic events and cause neo-cancerogenesis in a short time, they could still cause non-genotoxic pro-carcinogenic effects by triggering an exaggerated inflammatory re-action, compromising immune homeostasis, stimulating cell proliferation, and nega-tively affecting cellular stress response and damage repair machinery. This could re-sult in the promotion of regrowth of dormant micrometastases or relapse of stable minimal residual disease. Such a harmful outcome may likely result from a synergy between the virus and the vaccine, especially in multi-vaccinated and multi-infected individuals. Here, I bring the cell pathologist's point of view and discuss the multiple possible mechanisms by which the virus and the anti-COVID-19 mRNA vaccine might favor tumorigenesis. While a causal link cannot be established at this stage, knowledge of potential carcinogenic risks could help doctors and health policymakers take the best actions to protect vulnerable patients and convince the vaccine developer to de-sign a vaccine free from such harm.