Getting a two-year head start on cancer
BELFAST, Northern Ireland—Ovarian cancer is among the more difficult cancers to treat primarily because it is so often not discovered until it has spread within the pelvis and abdomen, thus making it much harder to treat. So as one could imagine, being able to identify it earlier, when the disease is more treatable, would be highly desirable.
And so it is that researchers from Queen’s University Belfast—in partnership with the University of New South Wales Australia, University of Milan, University of Manchester and University College London—are trying to meet that need, having developed a test that may be able to detect ovarian cancer up to two years earlier than current approaches.
The researchers discovered that the presence of four proteins together, known as a biomarker panel, indicates the likelihood of at least one type of ovarian cancer: epithelial ovarian cancer (EOC). They then developed a screening test using these biomarkers to achieve better cancer detection results.
“Firstly, we discovered that the presence of the biomarker panel will enable us to detect EOC. We then developed a screening test to detect this biomarker panel, making this a relatively simple diagnostic test,” explained Dr. Bobby Graham from the School of Biological Sciences at Queen’s University Belfast and lead author of the study. “The algorithm designed will screen the blood sample and flag any abnormal levels of the proteins associated with the cancer. The screening test identifies ovarian cancer up to two years before the current tests allow.”
The study, published in the journal Nature under the title “Diagnosis of epithelial ovarian cancer using a combined protein biomarker panel,” involved the analysis of blood samples from 80 individuals across a seven-year period.
Added Dr. Rachel Shaw, research information manager at Cancer Research UK: “Around half of ovarian cancer cases are picked up at a late stage, when treatment is less likely to be successful. So developing simple tests like these that could help detect the disease sooner is essential. At Cancer Research UK, we’re working hard to find new ways to detect cancer early and improve the tests already available. It’s really exciting to see these encouraging results for this type of ovarian cancer.”
The test is potentially very helpful because the majority of ovarian cancers are EOC. And the benefits of early detection cannot be overstated, as there is a 90-percent chance of five-year survival if EOC is diagnosed at stage one, compared to 22 percent if diagnosed at a stage three or four.
The work of assessing the test isn’t done yet, though, with Graham noting, “The results of this study are encouraging; however, we now want to focus on testing it in a wider sample set so that we can use the data to advocate for an ovarian cancer screening program.”
That wider sample set for future work is important because, as the authors point out in the paper, “A caveat to the current model that should be borne in mind is that the number of controls (141 samples from 31 women) may underestimate the variability of expression of these proteins in women without ovarian cancer. Higher variability would reduce the specificity of the test, reduce the PPV [positive predictive value] of risk estimates and erode the confidence in diagnosis.”
The four-biomarker model was not trained against the Type I EOC cases, the study authors point out in the paper, writing that “The Type I EOCs have different histology and are less aggressive than the Type II cases. Although not truly independent in the sense that they derive from a separate study, they provide a challenge to the model trained against Type II cases. Sensitivity of the model to the Type I cases shows the model is not merely sensitive to the samples it was trained against but is finding a real signal.”