Researchers found that infecting mice with respiratory syncytial virus (RSV) reduced breast cancer cells' ability to form tumors in the lungs by 65 to 70 percent. The effect stems from type I interferons, proteins that fight viral replication and hinder cancer cell seeding. The study raises hopes for drugs mimicking this mechanism.
Scientists at Imperial College London infected 23 mice intranasally with RSV, a virus causing cold-like symptoms, while 16 control mice received saline. Twenty-four hours later, all mice were injected with breast cancer cells. After 28 days, the RSV group showed 65 to 70 percent fewer tumor nodules in their lungs compared to controls, though nodule sizes were similar in both groups, indicating the virus mainly blocks initial seeding rather than growth. Cecilia Johansson, the lead researcher, called the findings 'very exciting,' noting no prior study had demonstrated this effect. She said, 'This is very exciting; no study has shown what we have shown.'