When the results from both methods were compared with the findings at surgery, the researchers found that ultrasound correctly classified 93 percent of tumors as cancerous or not, while the blood test was correct in only 83 percent of cases.
"The IOTA study not only demonstrated that ultrasound is better than blood tests but also that the blood tests do not give additional benefit in mathematical models developed to distinguish between benign and malignant masses," Timmerman said.
Timmerman emphasized that the study only looked at the best method to decide if a tumor was cancerous after the mass had already been discovered. "Of course, this is different from screening," he said. "In screening studies, a healthy population is screened for a specific disease, for example, ovarian cancer. In that setting, a blood test might prove to be useful in the future." He noted that two large studies exploring that issue are expected to conclude in about five years.
Dr. Robert Morgan, co-director of the gynecologic oncology/peritoneal malignancy program at the City of Hope Cancer Center in Duarte, Calif., said the study results confirm what doctors have known for a long time. "CA-125 is only elevated in about 50 percent of early stage ovarian cancer, and the data in this paper confirms that," he said.
The study's bottom line: Most of these cancers are being picked up with ultrasound, not the blood test, Morgan said. "And, most of the time, when [the ultrasound] says it's not malignant, it's not," he said.
''C-125 tests are not cheap and, particularly when you do them in a huge number of patients, the costs add up. And, apparently, they don't seem to be adding anything to the diagnostic accuracy," he
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