Even for early ovarian cancer, a panel of six biomarkers can detect the disease with high accuracy, according to results of a case-control analysis here.
In the phase II case-control study, the six-marker ovarian cancer panel had an overall sensitivity at all stages of 95.3% and a specificity of 99.4%, according to Gil Mor, M.D., Ph.D., of Yale, and colleagues.
Broken down by stage I and II disease, the panel was slightly less accurate, but still better than the early disease sensitivity of less than 60% for CA-125, the only test currently available, Dr. Mor and colleagues reported in the Feb. 15 issue of Clinical Cancer Research.
Given that ovarian cancer is difficult to detect in its early stages and difficult to cure when detected later, the new test may improve survival rates, Dr. Mor said.
"The ability to recognize almost 100% of new tumors will have a major impact on the high death rates of this cancer," Dr. Mor said. "We hope this test will become the standard of care for women having routine examinations."
The researchers divided their cohort into a training set and test set. The training set, including 181 healthy volunteers and 113 women with recently diagnosed ovarian cancer, had blood samples tested using several different panels in a multiplex assay.
Next, using the six-marker panel, Dr. Mor and colleagues performed a blinded evaluation of samples from a test set -- 181 healthy women and 43 from newly diagnosed ovarian cancer patients who had not been part of the first analysis.
The model correctly classified 221 out of 224 specimens in the test set, with a classification accuracy of 98.7%, the researchers said.
Dr. Mor and colleagues noted that when the two sets were combined, the six-marker panel misclassified two of the 362 samples from healthy volunteers and five of 156 samples from cancer patients.
Of the 36 stage I and II samples, four were misclassified. One of 120 stage III and IV samples was misclassified.
Overall, the researchers said, the positive predictive value of the test was 99.3% and the negative predictive value was 99.2%.
The work built on earlier research by Dr. Mor and colleagues on a four-marker panel that included leptin, prolactin, osteopontin, and insulin-like growth factor II. (See: Four-Protein Panel Predicts Early Ovarian Cancer)
For this study, the researchers added two other biomarkers -- macrophage inhibitory factor and CA-125 -- and tested the combination in a cohort of 518 women. Some of the findings were reported at a meeting early last year. (See: SGO: Ovarian Cancer Screening Test Found Highly Accurate)
CA-125 is currently used as a biomarker for ovarian cancer in high-risk groups, but it is not regarded as sufficiently sensitive, especially in early-stage disease, Dr. Mor said.
The test is currently being evaluated in a phase III multicenter clinical trial involving nearly 2,000 patients.
Visintin I, et al "Diagnostic markers for early detection of ovarian cancer"Clin Cancer Res 2008; 14: 1065-72.
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