In Brief: Blood test for ovarian cancer shows promise in early study
Blood test for ovarian cancer shows promise in early study
In 2008 in the United States, about 22,000 women will be diagnosed with ovarian cancer, and 15,500 will die of the disease. Though much less common than breast cancer, which strikes more than 182,000 women each year, ovarian cancer is three to four times more lethal. The reason it's so deadly is that it grows deep within the body and rarely produces unequivocal symptoms until it has spread beyond the ovary and become largely incurable. A screening test for the early detection of ovarian cancer could save many lives. Now, researchers at Yale University report encouraging results from a blood test based on a set of proteins thought to be active in response to early tumor development. Findings published in the Feb. 15, 2008, issue of Clinical Cancer Research suggest that in women at high risk for ovarian cancer, the test can accurately distinguish those who have the disease from those who don't.
Using a panel of six protein biomarkers, the researchers analyzed blood samples from 156 women with newly diagnosed ovarian cancer and 362 healthy women at high risk for the disease. No single biomarker distinguished healthy cells from cancer cells, but the six-protein combination distinguished disease-free women from ovarian cancer patients with an overall sensitivity of 95.3% and a specificity of 99.4%. That means the test correctly identified 95.3% of those who had the disease and 99.4% of those who did not. CA-125, the only ovarian cancer screening test currently available, has a sensitivity of less than 60% in detecting early-stage ovarian cancer and a very poor specificity (many other conditions can elevate CA-125). Specificity is extremely important because invasive surgery is the only way to know for sure if a woman has ovarian cancer.
The new blood test looks for the proteins leptin, prolactin, osteopontin, insulin-like growth factor II, macrophage inhibitory factor, and CA-125. According to the researchers, the body responds to cancer cells by changes in levels of some of these proteins, even at the earliest stages of the disease.