Shocking Yet Hopeful: COVID’s Lessons on the Virus and Cancer Connection
The evolving COVID and cancer relationship is delivering eye-opening insights for physicians across the United States years after the pandemic’s peak. Fresh research reveals how SARS-CoV-2 and other respiratory viruses can influence existing cancers in surprising ways, reshaping what doctors understand about viral infections and cancer risk.
Millions of Americans who recovered from COVID-19 now face new questions about their long-term health. Studies show the virus does not typically create cancer from scratch the way some longstanding oncoviruses do. Instead, it can dramatically alter the behavior of cells already present in the body.
Mark Smith
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Researchers have long known that certain viruses contribute to roughly 15-20% of cancers worldwide. Human papillomavirus drives cervical and other cancers. Hepatitis B and C fuel liver tumors. Epstein-Barr virus links to lymphomas and nasopharyngeal cancers. These connections involve direct genetic changes or chronic inflammation.
The COVID-19 pandemic gave scientists an unprecedented real-world laboratory. With hundreds of millions of infections in the U.S. alone, clear patterns emerged about how acute viral illness interacts with cancer biology.
One major finding centers on awakening dormant cancer cells. A University of Colorado Cancer Center team led by Dr. James DeGregori used animal models and large human datasets, including the UK Biobank and U.S. Flatiron Health records. They discovered that respiratory viruses like SARS-CoV-2 or influenza can trigger inflammation that reactivates quiet cancer cells, particularly in the lungs of breast cancer survivors.
In mice with dormant breast cancer cells, infection caused explosive growth of metastatic tumors. Human data from 2020 showed cancer survivors who contracted COVID faced substantially higher odds of dying from their cancer in the following year. Dr. DeGregori compared dormant cells to embers in a campfire and viral infection to a strong wind that reignites the flames.
This matters for the more than 18 million Americans living with a history of cancer. Many carry microscopic dormant cells controlled by the immune system for years. A severe viral infection can tip the balance through inflammatory signals such as interleukin-6.
The pandemic also created another challenge. Nearly 9.4 million routine cancer screenings for breast, colorectal, and prostate cancers were missed in 2020 alone. Breast cancer screening volumes dropped as much as 90% in April of that year. While diagnoses rebounded in later years, experts worry some cases advanced undetected, leading to more complex treatment needs today.
On the other side of the story, a Northwestern Medicine study published in the Journal of Clinical Investigation in late 2024 uncovered a potential silver lining. SARS-CoV-2 RNA can activate a unique population of immune cells called inducible nonclassical monocytes, or I-NCMs. These cells infiltrate tumors, recruit natural killer cells, and help shrink cancers including melanoma, lung, breast, and colon tumors in preclinical models.
Dr. Ankit Bharat, who led the work, noted the cells’ special ability to enter tumor environments where ordinary immune cells cannot. The finding raises hope for new therapies that mimic this viral-triggered response, especially for patients whose cancers resist current immunotherapies.
Taken together, these discoveries highlight the lessons from the COVID-19 pandemic for oncology and virology. Viral infections do not act as simple on-off switches for cancer. They can fuel progression through inflammation in some cases while sparking powerful anti-tumor immunity in others. The massive scale of COVID-19 made these dual effects visible at population level for the first time.
For everyday Americans, the practical takeaway centers on protection and vigilance. Cancer patients and survivors remain at higher risk for severe outcomes from COVID-19 and other respiratory viruses. Staying up to date on recommended vaccinations helps reduce infection severity and may lower secondary risks tied to inflammation. Resuming and maintaining age-appropriate cancer screenings remains essential after the disruptions of 2020 and 2021.
Healthcare systems also learned hard lessons about maintaining preventive care during crises. Delayed diagnoses carry real economic and personal costs, from higher treatment expenses to lost productivity for patients and families.
Public reaction has been a mix of concern and cautious optimism. Many survivors appreciate the new focus on infection prevention, while others express anxiety about added risks. Doctors stress that these findings do not mean every COVID survivor will see cancer return. They do mean that protecting vulnerable immune systems and catching cancers early continue to save lives.
The SARS-CoV-2 and cancer story is still unfolding. Ongoing research explores whether milder infections or vaccination status change the risks observed in 2020 data. Scientists are also testing ways to harness beneficial immune pathways sparked by the virus for new treatments.
These insights from the COVID-19 era are already guiding smarter strategies in cancer care. They remind physicians and patients alike that the relationship between viruses and cancer is far more nuanced than once thought. For millions of Americans, staying informed and proactive with screenings and vaccinations offers the best path forward as science continues to unravel these complex connections.
