Oncologists repeatedly complain that participation rates in early cancer detection programs are too low. The following applies with the iron law: If a malignant tumor is detected early, the chances of a cure increase enormously.
One of the main reasons for this will be that the effort required is sometimes considerable and healthy people are reluctant to put such a seemingly unnecessary burden on themselves. Indeed, colonoscopies, x-rays of the female breast or prostate palpation are sometimes inconvenient – and even expensive for the healthcare system.
The hope is that simpler and cheaper tests could revolutionize early diagnosis. Researchers from Chalmers University of Technology in Gothenburg now they have taken a big step towards this hope. They managed to detect 14 types of cancer, such as urological and gynecological, at an early stage using a combined urine and blood test.
The detection rate for 14 different cancers was 63%.
The idea behind it: Malignant tumors release modified sugar molecules into the blood, which are also found in the urine. These so-called glycosaminoglycans (GAGs) are among the biomarkers with which cancer cells can be detected in blood and urine. The molecules can be found in blood and urine samples using mass spectrometry.
The Gothenburg researchers write that only five percent of the 1,260 subjects included in the study had false-positive results. So the specificity of their test is 95%. When combined with a urine sample, the sensitivity, i.e. corrected positive cancer results, was 62.3%. This means that about six out of ten cancer patients are identified correctly, four receive a false negative result.
Experts are still cautious about Gothenburg’s results. Ulrich Keilholz, director of the Charité Comprehensive Cancer Center, says it’s an “exciting step” but not yet the breakthrough for better early detection. “This is another building block of cancer medicine, and ultimately, a revolution always consists of several individual steps.”
Five percent of false-positive cancer diagnoses are too many for a screening program.
Ulrich Keilholz, oncologist
The 62 percent detection rate of a malignancy isn’t intoxicating, says Keilholz. Although this rate is not that far from DNA evidence, it reaches 70 percent.
The false positive rate is even more problematic than the small number would suggest at first glance. “Five percent false positive cancer diagnoses is too much for a screening program.” With 10,000 tests, that’s 500 people who need to be unnecessarily scared of cancer and need to have biopsies. “Anything less than 99 percent does too much damage.”
But the GAGs offer even more hope in another direction. These biomarkers are not only used for early diagnosis, but also for the characterization of tumor cells, for example to be able to evaluate the response to chemotherapy or immunotherapy. So far, these blood cancer biomarkers are cancer cells swimming in the blood or their DNA remnants. But not all cancers spread or release enough DNA components into the blood for detection. Research is therefore increasingly focused on the altered proteins in the blood, including glycans.
For this important characterization of tumors, he sees a far greater contribution from glycans, which the Swedish researchers highlighted in their work, although they are not yet sufficient for direct clinical application. But the approach is “totally exciting,” says Keilholz. The Charité is also carrying out similar research projects.
Read all parts of the columns that have appeared so far on the column page of the Tagesspiegel.
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