NEWPORT BEACH, California — Researchers in California have identified a molecular signal in blood that can reveal ovarian cancer at its earliest precancerous stage, long before a tumour forms or symptoms appear. The signal, an RNA molecule called Tu-Stroma, detected the precancerous condition known as serous tubal intraepithelial carcinoma (STIC) in 92.3 percent of women who had it in a validation group, while correctly identifying 98.2 percent of healthy women, according to a study published on 10 November 2026 in Nature Medicine . The work, led by researchers at the Hoag Family Cancer Institute, offers the first realistic prospect of a blood-based early warning system for high-grade serous ovarian cancer, the most common and most lethal form of the disease. The cancer often begins not in the ovary but in the fallopian tube, as microscopic abnormal cells invisible to imaging and conventional blood tests. By the time most cases are found, the disease has already spread. A test that ...