Scientists at Dana-Farber Cancer Institute have identified a subtype of ovarian cancer able to build its own blood vessels, suggesting that such tumors might be especially susceptible to anti-angiogenic drugs, which block blood vessel formation. In a study published in the online journal PloS ONE, the investigators estimate that the subtype may account for a third of all serous ovarian cancers, a common cancer of the surface of the ovaries. The discovery of the subtype, made by analyzing data from the clinical records of more than 1,500 serous ovarian cancer patients and samples of their tumors, may spur clinical trials to determine if patients with the subtype can benefit from anti-angiogenic therapies now being tested in other cancers.