A molecular signal in the blood helps identify microscopic changes that precede development of ovarian cancer, researchers have found, ⁠a potential diagnostic breakthrough for a disease often ⁠discovered after it has already spread.For decades, ​efforts to detect ovarian cancer earlier have focused on finding smaller tumors, the researchers noted in their report published on Tuesday in Nature Medicine.“We asked a fundamentally different question: What if we could identify the earliest molecular warning signs before invasive cancer even develops?” study leader Rajan Gogna of the Hoag Family Cancer Institute in ⁠Newport Beach, California, said in a statement.Ovarian cancer often begins with microscopic changes in the lining of the fallopian tubes. The precancerous lesions are known as serous tubal intraepithelial carcinoma.The new study found that women with this precursor condition have elevated blood levels of an RNA molecule called Tu-Stroma.When researchers measured Tu-Stroma in blood, they detected STIC in 92.3% of affected women ⁠and correctly identified 98.2% of healthy women.In women with genetic risk factors for ovarian cancer, approximately 72% of positive results would be accurate, while negative results would be correct nearly 100% of the time, they reported.“For women at high risk, this ​could transform how we approach prevention,” co-author Dr Esha Madan, also of Hoag, said in a statement.Many such women ‌face difficult decisions about preventive surgery to remove their fallopian tubes ‌and ovaries.“Today, decisions about preventive surgery are largely guided by inherited risk, without knowing whether precancerous lesions are actually present,” Madan said. “Our discovery could eventually provide that missing biological information.”