A sweeping analysis of electronic health records covering more than 45,000 cancer patients has found that those who received an mRNA COVID-19 vaccine within a few months of starting cancer immunotherapy lived significantly longer than comparable patients who did not receive a recent vaccine. The survival benefit was observed across multiple cancer types and appeared strongest in patients vaccinated in the months immediately before beginning their cancer treatment.
The findings, published in JAMA Oncology, are observational and cannot definitively prove that the vaccine caused the improved survival. However, researchers say the magnitude, consistency, and biological plausibility of the effect across radically different cancer types and treatment regimens is highly compelling.
Priming the Immune System
The leading hypothesis is that mRNA vaccines activate dendritic cells and T-cell signaling pathways that overlap significantly with those targeted by cancer checkpoint inhibitor immunotherapies. This "priming" effect may leave the immune system in a heightened state of alertness that translates to a stronger anti-tumor response when the cancer drugs are introduced.
"It is biologically plausible that vaccination creates an immunological environment more permissive to the anti-tumor immune response," said Dr. James Park of Memorial Sloan Kettering Cancer Center. "This finding warrants urgent prospective clinical trials."