A new study is adding COVID-19 to the long list of things doctors want to keep an eye on, suggesting that people who recovered from the virus have a small but measurable increase in their later risk of developing lung cancer. The signal is strongest in current and former smokers. Researchers paired a large electronic health record analysis with lab experiments and zeroed in on an enzyme that seems to connect the virus's spike protein with lung scarring and tumor-friendly inflammation. The overall risk bump is modest, but the molecular data have scientists calling for longer follow-up of COVID survivors.
Study Methods And Main Numbers
The team pulled de-identified records from the TriNetX Research Network and matched patients by demographics, then compared how often new lung cancer developed after documented SARS-CoV-2 infection. In the matched cohorts (about 166,807 patients), current smokers with recorded COVID-19 developed lung cancer at a rate of 1.7% versus 1.4% in comparable smokers without COVID. Former smokers showed 1.5% versus 1.2%, and never-smokers had smaller increases. The study details the risk and hazard ratios in Frontiers in Immunology.
What Happened In The Lab
To probe the biology, researchers turned to mice. Animals received intratracheal doses of recombinant SARS-CoV-2 spike protein and were run through a standard urethane-induced lung cancer protocol. Spike exposure led to acute lung injury, neutrophil buildup, microthrombi and more aggressive tumors. When mice lacked thymidine phosphorylase (TYMP), those problems dropped sharply, with much less injury and far fewer tumor-bearing lung lobes. Tumor incidence went from about 50% of lobes to 18% in TYMP-deficient animals. A news release from Marshall University, which co-led the work, highlighted TYMP as a possible drug target.
How Strong Is The Evidence?
The authors are careful to say the clinical analysis is retrospective, so it shows an association rather than proving that COVID-19 causes lung cancer. They also point out that the mouse work used isolated spike protein, not live virus infection. That means the animal data support a plausible mechanism but do not by themselves show that real-world SARS-CoV-2 infections will have the same effect in people. These limitations, along with the main findings, are laid out in Frontiers in Immunology.
What It Means For Patients
The absolute increases are small, roughly three-tenths of a percentage point among smokers, so an individual person's chance of developing lung cancer remains low even if their relative risk is nudged upward. Clinicians and public health planners still see the findings as important, since fibrosis and chronic inflammation are already known cancer risks and a documented COVID history could influence future surveillance or diagnostic decisions. Current U.S. guidance continues to call for annual low-dose CT screening for people aged 50 to 80 with a 20 pack-year smoking history, as outlined by the U.S. Preventive Services Task Force.
Why It’s Back In The News
The paper first appeared online in late March and was promoted by Marshall University in April. Coverage resurfaced this week after additional outlets recapped the results, including a May 17 piece in the Dallas Express. Researchers say the renewed spotlight underscores the need for long-term follow-up and clinical studies that can test whether blocking TYMP might reduce fibrosis and tumor promotion. As Marshall University noted in its news release, the authors hope their work will help shape both monitoring and future therapeutic research.
Next Steps For Researchers
Next on the wish list are prospective human studies with longer follow-up, better data on vaccination and exposure history, and single-cell analyses to trace how TYMP reshapes the lung microenvironment. The group also points to the mouse findings, where TYMP deficiency reduced tumor formation, as a reason to move ahead with preclinical testing of TYMP-targeting strategies. Coverage in outlets such as MedicalXpress places the new work in a broader pattern of research tying viral pneumonia and persistent inflammation to later oncogenic changes in lung tissue.
Bottom Line
The study does not show that COVID-19 will cause lung cancer in most people, but it raises a biologically plausible concern that survivors, especially those with smoking histories or lasting lung damage, may benefit from continued monitoring. If you have ongoing respiratory symptoms after COVID or you already meet screening criteria because of a smoking history, it is worth asking your clinician whether low-dose CT scans or other follow-up make sense for you.
