Cancer uses antioxidants to disarm the immune system, scientists discover

Scientists have discovered that tumors release natural antioxidants to shut down the immune cells responsible for destroying cancer, exploiting a surprising weakness in the body's defenses. Blocking this mechanism in mice restored immune activity and improved immunotherapy responses, potentially opening a new path toward more effective cancer treatments. Free radicals have traditionally been associated with damage to the body's cells, leading to widespread interest in whether antioxidants might help prevent cancer. But new research suggests these often misunderstood molecules also play an important role in protecting us from the disease. Scientists have discovered that certain immune cells actually need small amounts of reactive oxygen species, a group of molecules that includes free radicals, to recognize and destroy cancer cells.

Even more surprisingly, tumors appear to exploit this requirement by releasing natural antioxidants that interfere with the immune system's ability to fight back. The findings, published in the journal Science, reveal a previously unknown way that cancer evades the body's defenses. They could also point toward new strategies for making cancer immunotherapies more effective, particularly in patients whose tumors resist existing treatments. The immune system protects the body by identifying and eliminating threats, ranging from harmful bacteria and viruses to abnormal cells that can develop into cancer. Among its most important defenses are