Respiratory Infections and Cancer Metastasis: A Reactivation Cascade

Viral Infections Reignite Dormant Cancer Cells Like Embers in the Wind

New research suggests that common respiratory infections, such as the flu and COVID-19, can awaken dormant cancer cells in the lungs, possibly leading to metastasis. Scientists from the University of Colorado have likened this phenomenon to reigniting embers of a campfire.

“The resting cancer cells are like the embers of an abandoned campfire, and the airways like a strong wind that rekindles the flames,” explained senior author james Degregori.The study delves into the mechanisms behind this reactivation. Infected lung cells release meaningful amounts of Interleukin-6 (IL-6),an inflammatory messenger. This IL-6 triggers a cascade within dormant cancer cells, reactivating them. Though, researchers noted that this alone doesn’t fully explain the rapid growth of these reawakened cells months after the infection has cleared, indicating the involvement of other factors.

Further analysis revealed that “reprogrammed” immune cells also contribute to metastasis. Specifically, T-helper cells (CD4+) appear to suppress T killer cells, hindering their ability to identify and eliminate cancer cells.

Human Data Corroborates Findings

to determine if these findings translate to humans, the researchers examined epidemiological data from 2020, the initial phase of the COVID-19 pandemic. They analyzed mortality rates for over 35,000 breast cancer patients in the USA and approximately 4,800 cancer patients in Great Britain.The results were striking: cancer patients who tested positive for COVID-19 exhibited nearly double the mortality rate compared to uninfected patients.Similarly, breast cancer patients in the US who contracted COVID-19 were 50% more likely to develop lung metastases than those who remained uninfected.

potential for Prevention and therapies

This epidemiological data provides strong evidence for the link between respiratory viral infections and the resurgence of dormant lung cancer cells. “Our results indicate that cancer survivors, after respiratory infections, could have an increased risk of recurring metastases,” stated co-author Roel Vermeulen.

The discovery of IL-6 as a key factor in awakening cancer cells opens avenues for new preventive and therapeutic strategies. “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,” noted Aguirre-Ghiso. Further clinical studies are needed to confirm the efficacy of these approaches.

Source: University of Colorado Anschutz Medical Campus
Publication: Nature, 2025; DOI: 10.1038/s41586-025-09332-0
Date: July 31, 2025

how do platelet activation and aggregation contribute to cancer metastasis following a respiratory infection?

The Interplay Between Viral Infections & Cancer Spread

The connection between respiratory infections – like influenza, pneumonia, and even COVID-19 – and cancer metastasis is increasingly recognized as a critical area of oncological research. It’s no longer simply about immunosuppression; a complex cascade of events is triggered,possibly reactivating dormant cancer cells and accelerating the spread of existing tumors. This article delves into the mechanisms behind this risky interplay, exploring how viral infections can fuel cancer progression and what preventative measures can be taken. We’ll focus on the biological pathways involved,the types of cancers most vulnerable,and emerging therapeutic strategies.

How Respiratory infections Initiate the Metastatic Cascade

The link isn’t always direct, but several key mechanisms explain how a lung infection or systemic respiratory virus can contribute to metastasis:

Inflammation & the Tumor Microenvironment: respiratory infections induce a strong inflammatory response. Chronic inflammation is a hallmark of cancer and creates a permissive tumor microenvironment (TME). This TME supports angiogenesis (new blood vessel formation), immune suppression, and epithelial-mesenchymal transition (EMT) – all crucial steps in metastasis.

Epithelial-Mesenchymal Transition (EMT): Viruses can directly induce EMT in cancer cells, allowing them to detach from the primary tumor and gain migratory capabilities. EMT in cancer is a key driver of metastatic potential.

Immune Suppression: Many respiratory viruses temporarily suppress the immune system.This allows cancer cells to evade immune surveillance and establish themselves in distant sites.Specifically, infections can deplete cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, critical for cancer control.

Increased Vascular Permeability: Inflammation increases the permeability of blood vessels, making it easier for cancer cells to enter the circulation – a necessary step for distant metastasis.

Platelet Aggregation: Infections can trigger platelet activation and aggregation. Cancer cells can “hide” within these platelet clumps, shielding themselves from immune attack and facilitating their transport to distant organs.

Specific Viruses & Their Impact on Cancer Metastasis

Certain viruses have been more strongly linked to increased cancer risk and accelerated metastasis:

Influenza virus: Studies suggest influenza infection can promote lung cancer metastasis, especially in pre-existing tumors. The inflammatory response and immune suppression are key factors.

Human Respiratory Syncytial Virus (RSV): RSV has been shown to enhance the metastatic potential of certain breast cancer cell lines in vitro and in vivo.

COVID-19 (SARS-CoV-2): Emerging evidence suggests COVID-19 can exacerbate cancer progression and metastasis, potentially due to its severe inflammatory response and impact on immune function. Delayed cancer screenings during the pandemic also contributed to later-stage diagnoses and potentially increased metastatic rates.

Pneumonia-Causing Bacteria: Bacterial pneumonia, while not a virus, induces a similar inflammatory cascade and can contribute to cancer spread.

Cancers Most Vulnerable to Infection-Driven Metastasis

While any cancer can potentially be affected, some exhibit a stronger correlation with respiratory infection-induced metastasis:

Lung Cancer: The most obvious connection, given the direct impact of respiratory infections on the lungs.

Breast Cancer: Several studies have demonstrated a link between viral infections (RSV, influenza) and increased breast cancer metastasis.

Colorectal Cancer: Inflammation plays a important role in colorectal cancer advancement and progression, making it susceptible to infection-driven exacerbation.

Melanoma: Immune suppression induced by infections can allow melanoma cells to evade immune control and metastasize.

Prostate Cancer: Emerging research suggests a link between chronic inflammation and prostate cancer progression,potentially influenced