There is no evidence that COVID-19 directly causes cancer the way viruses like HPV or hepatitis B do. SARS-CoV-2 is not classified as an oncogenic (cancer-causing) virus. However, the relationship between COVID and cancer is more nuanced than a simple no. The virus interferes with several cellular defense systems that protect against cancer, it triggers prolonged inflammation linked to tumor growth, and the pandemic itself disrupted millions of cancer screenings. Each of these deserves a closer look.
How Known Cancer Viruses Differ From SARS-CoV-2
Seven viruses are firmly established as causes of cancer in humans, including HPV, hepatitis B, hepatitis C, and Epstein-Barr virus. These viruses cause cancer through specific, well-understood mechanisms. HPV, for example, produces two proteins (E6 and E7) that directly destroy the cell’s built-in tumor suppression systems, immortalizing cells and driving them toward malignancy. Hepatitis B and C cause cancer primarily by establishing chronic infections that last years or decades, inflaming liver tissue until cells begin dividing abnormally.
SARS-CoV-2 doesn’t work this way. It causes an acute respiratory infection, not a chronic one that lingers in tissue for years. Cervical cells, for instance, barely express the receptor the virus needs to enter, so it can’t infect the same tissues HPV targets. The virus doesn’t carry dedicated cancer-causing genes. That distinction matters: COVID is not in the same category as HPV or hepatitis when it comes to directly transforming healthy cells into cancerous ones.
What the Virus Does to Your Cells’ Defenses
While SARS-CoV-2 isn’t a cancer virus, research published in Nature shows it disrupts several of the same protective systems that keep cancer in check. The most significant finding involves DNA repair. Two viral proteins, ORF6 and NSP13, destroy a key enzyme called CHK1 that cells rely on to fix damaged DNA during normal division. When CHK1 is depleted, cells run low on the molecular building blocks they need to copy DNA accurately. The result is stalled cell division, accumulated DNA damage, and activation of inflammatory pathways.
On top of that, the virus’s N-protein interferes with another repair system by blocking a protein called 53BP1 from reaching the site of DNA breaks. Normally, 53BP1 acts like a first responder, arriving at a broken strand of DNA and coordinating the repair crew. The N-protein essentially prevents this responder from showing up, leaving DNA damage unrepaired. These findings have been confirmed in infected mice and in patients hospitalized with COVID-19, not just in lab dishes.
The virus also degrades p53, often called the “guardian of the genome” because it’s the single most important protein preventing cells from becoming cancerous. SARS-CoV-2 uses enzymes called papain-like proteases to tag p53 for destruction through the cell’s waste-disposal system. With p53 levels lowered, the cell loses a critical checkpoint: the ability to stop dividing when something goes wrong, or to self-destruct when damage is too severe. This creates a cellular environment more permissive to errors that could, over time, accumulate toward cancer.
Cellular Aging and the Tumor Environment
When DNA damage piles up and repair systems falter, cells often enter a state called senescence, a kind of permanent retirement where they stop dividing but don’t die. Senescent cells aren’t inert. They pump out inflammatory signals that can damage neighboring tissue and, in the context of cancer biology, create a microenvironment that helps tumors grow. Cellular senescence is now recognized as a key factor in severe COVID-19, and it’s long been implicated in cancer development and aging-related diseases.
Chronic Inflammation as a Bridge
One of the clearest links between COVID and cancer risk runs through inflammation. In severe COVID and in long COVID, the body produces elevated levels of inflammatory molecules, particularly IL-6, TNF-alpha, and IL-1 beta, along with activation of signaling pathways like NF-kB and STAT3. These aren’t obscure lab markers. They’re the same inflammatory signals found inside tumors, where they help cancer cells survive, grow blood vessels, evade the immune system, and spread.
This overlap between post-COVID inflammation and the tumor microenvironment is a growing area of concern. Chronic infections from hepatitis B and C, HIV, and other viruses are already known to elevate IL-6 levels, which can weaken the immune cells responsible for killing both virus-infected and cancerous cells. When IL-6 stays elevated for months, as it can in long COVID, it impairs the ability of certain immune cells to destroy abnormal tissue. Whether this translates into measurably higher cancer rates in COVID survivors is still an open question, but the biological plumbing is there.
The Screening Gap That Already Has Consequences
Perhaps the most concrete connection between COVID and cancer has nothing to do with the virus itself. During the early months of the pandemic, cancer screening volume dropped by 86% to 94% compared to prior years. Between mid-March and mid-June 2020 alone, an estimated 285,000 breast cancer screenings, 95,000 colorectal screenings, and 40,000 cervical exams were missed. Across the entire U.S. population, the total screening deficit reached roughly 3.9 million for breast cancer, 3.8 million for colorectal cancer, and 1.6 million for prostate cancer.
The downstream effect was immediate. Cancer diagnoses dropped 19% to 78% during that period, not because fewer people had cancer, but because fewer cancers were being found. Researchers estimate that this screening backlog will lead to approximately 10,000 excess deaths from breast and colorectal cancer over the next decade in the United States. Cancers caught at later stages are harder to treat and less likely to be cured, so the pause in routine screening has real, lasting consequences that are still unfolding.
What the Cancer Incidence Data Shows So Far
National Cancer Institute data puts the 2022 rate of new cancer cases at 462.8 per 100,000 people. Between 2018 and 2022, overall cancer incidence rose by an average of 0.4% per year. The 2020 data point was excluded from trend calculations because the screening collapse that year artificially suppressed new diagnoses. It’s too early to determine whether post-pandemic incidence rates reflect a genuine increase tied to the virus or simply a rebound from delayed diagnoses catching up. Disentangling the two will take years of data.
The NIH has committed $515 million to its RECOVER initiative, which is specifically investigating how SARS-CoV-2 infection affects long-term risk for diseases including diabetes, cancer, and neurological disorders. Those studies are in development, and their results will be the first large-scale attempt to answer whether COVID survivors face elevated cancer risk compared to people who were never infected.
A Surprising Finding About mRNA Vaccines and Cancer Treatment
One unexpected development has come from studies on mRNA COVID vaccines in cancer patients. A large retrospective study at MD Anderson Cancer Center found that patients who received an mRNA COVID vaccine within 100 days of starting immunotherapy (a treatment that helps the immune system attack tumors) had significantly improved survival compared to unvaccinated patients. This held true for non-small cell lung cancer and melanoma, with improvements in both median and three-year overall survival. The mRNA platform appeared to sensitize tumors to immunotherapy, essentially making the cancer treatment work better. This doesn’t mean vaccines prevent cancer, but it does counter any concern that mRNA vaccines promote it.
Putting the Risk in Perspective
The honest answer is that SARS-CoV-2 is not a cancer-causing virus in the traditional sense, but it temporarily weakens several of the body’s key anti-cancer defenses: it degrades the p53 tumor suppressor, impairs DNA repair, triggers prolonged inflammation, and accelerates cellular aging. Whether these transient disruptions translate into a meaningful increase in cancer risk years later remains unknown. The biological mechanisms are plausible and well-documented in lab studies and animal models, but population-level evidence linking COVID infection to higher cancer rates hasn’t materialized yet.
What has already caused measurable harm is the pandemic’s disruption of cancer screening, which delayed diagnoses for millions of people and is projected to cost thousands of lives over the coming decade. For anyone who skipped routine screenings during 2020 or 2021, catching up on those appointments is the most actionable step available right now.