Cancer Metastasis & Respiratory Infections
Table of Contents
New research reveals a concerning link between viral respiratory infections, like COVID-19, and the reactivation of dormant cancer cells, potentially leading to increased metastasis and mortality.
The “Campfire” Effect: How Infections Ignite Cancer Recurrence
Denver, CO – July 31, 2025 – A groundbreaking study from the University of Colorado Anschutz Medical Campus has shed light on a disturbing phenomenon: viral respiratory infections can act as a catalyst for cancer recurrence by awakening dormant cancer cells in the lungs. This process, likened to rekindling embers of a campfire, significantly increases the risk of metastasis, the spread of cancer to other parts of the body.
Senior author James Degregori from the University of Colorado explained the mechanism, comparing resting cancer cells to “embers of an abandoned campfire” and the airways to “a strong wind that rekindles the flames.” The research,published in Nature,details how infected lung cells release inflammatory messenger substances,most notably Interleukin-6 (IL-6). This cytokine triggers a cascade of reactions within dormant cancer cells, effectively reactivating them.
While the immediate reactivation is understood, the study also addresses why these awakened cancer cells exhibit accelerated growth months after the initial infection has subsided. Further analysis revealed that “reprogrammed” immune cells also play a crucial role in promoting metastasis. specifically, T-helper cells (CD4+) are found to inhibit T killer cells, thereby hindering the immune system’s ability to detect and eliminate cancer cells.
Unveiling the Mechanisms: IL-6 and Immune Cell Reprogramming
The research team meticulously investigated the molecular pathways involved in this cancer reactivation. They discovered that infected lung cells release substantial amounts of IL-6,a key inflammatory mediator. This surge in IL-6 initiates a signaling pathway within the dormant cancer cells, leading to thier reawakening and proliferation.
The prolonged growth observed months after infection suggests the involvement of additional factors beyond the initial inflammatory response. The study identified that certain immune cells,specifically T-helper cells,are altered by the viral infection. These reprogrammed T-helper cells actively suppress the cytotoxic functions of T killer cells, creating an environment where cancer cells can evade immune surveillance and grow unchecked. This dual action – reactivating cancer cells and suppressing the immune response – creates a potent combination that favors metastasis.
Evidence in Humans: A stark Correlation
To ascertain whether these findings translate to human patients, Chia and his colleagues analyzed epidemiological data from the early stages of the COVID-19 pandemic (2020). They examined the mortality rates of over 35,000 breast cancer patients in the USA and approximately 4,800 cancer patients in great Britain.
The results were stark: cancer patients who tested positive for COVID-19 exhibited nearly a twofold increase in mortality compared to their uninfected counterparts. Similarly, breast cancer patients in the United States who contracted COVID-19 developed lung metastases 50 percent more frequently then those who remained uninfected.These epidemiological findings strongly corroborate the experimental evidence, confirming a critically importent link between viral respiratory infections and the resurgence of dormant cancer cells in the lungs.
Implications for Prevention and Therapy: A New Frontier
The study’s findings offer critical insights into the complex interplay between infections and cancer metastasis, opening new avenues for prevention and therapeutic interventions. “Our results indicate that cancer survivors, after respiratory infections, could have an increased risk of recurring metastases,” stated co-author Roel Vermeulen from the University of Utrecht.
The identification of IL-6 as a pivotal factor in reactivating cancer cells presents a promising target for new treatments. “The discovery of interleukin-6 as a key factor for the awakening cancer cells suggests that the use of IL-6 inhibitors or other immunotherapies could prevent or weaken metastasis after a viral infection,” explained aguirre-Ghiso. Future clinical studies will be crucial to validate whether these therapeutic strategies can effectively mitigate the risk of cancer recurrence following viral respiratory infections.
Source: University of Colorado Anschutz Medical Campus
Date: July 31, 2025
Publication: Nature, 2025; DOI: 10.1038/s41586-025-09332-0