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Blood test for cancer

Global Goals & Global Society
Blood test for cancer

Until now, most cancer screening examinations have been costly and often unpleasant, as in the case of colonoscopy. If the suspicion of a tumor is already concrete, a biopsy brings clarity: For this, however, a sample of the suspicious tissue must be taken with a needle. It would be much easier, however, if cancer could simply be detected in the blood. Research into this is in full swing.

Many of the blood tests that have been developed look for tiny snippets of tumor genetic material in the blood. Others aim to detect cancer by looking for certain sugar molecules that change during cancer.The so-called Galleri test is currently particularly advanced: it looks for cancer DNA in the blood. According to the manufacturer Grail, more than 50 types of cancer can be detected by a routine blood sample. The test is also said to be able to identify the location of the cancer in the body. However, the test is not suitable for independent diagnosis. Rather, it serves as a supplement to the existing cancer screening examinations, recommends Grail.

First successesIn the USA, doctors are already allowed to perform the Galleri test. However, the test, which costs just under $1,000, is not currently covered by health insurers there. The FDA has not yet approved the test. However, an initial study involving around 6,600 subjects over the age of 50 has already provided initial data on the accuracy of the test: A cancer signal was detected in just under one hundred test subjects, and the cancer diagnosis was confirmed in 35 of them. This means that those who received a positive test result actually had cancer in almost 40 percent of the cases. Many of the cancers detected were still at an early stage. The majority were forms for which there is no routine cancer screening. A large study involving 140,000 volunteers is now underway in the United Kingdom to test the accuracy and usefulness of the method, but it will be years before it is clear whether the test is suitable for widespread use, says Susanne Weg-Remers, head of the Cancer Information Service at the German Cancer Research Center in Heidelberg. The physician assumes that particularly at-risk people could benefit from blood tests for cancer.

What to do in case of a false alarm?

The results of the study from the USA show: Almost two-thirds of those tested positive did not have cancer. That is one percent of the total number of test subjects. In the U.S., this is already posing new problems for practices and patients: "Of course, it is also a great burden on a healthcare system when a whole series of follow-up examinations are suddenly required, of which it is not yet known whether they would have been necessary at all," says Weg-Remers. Apart from the high costs that such examinations cause, the psychological burden on those affected can also be enormous. If the test is positive, further, possibly invasive, cancer examinations follow. If these are then negative, a worrying feeling often remains in the patients, according to Weg-Remers. This is another reason why blood tests for cancer are still considered problematic for early detection.

Blood tests have long been established to monitor the development of a cancer that has already been detected and to find the optimal therapy. They can also be used to check the success of cancer treatment and a possible relapse. Weg-Remers believes that it will take another ten to twenty years before blood tests for cancer detection are integrated into the overall concept of early cancer detection. And even then, they will have to be supplemented by conventional methods of early cancer detection, she says. But she is confident that the blood tests will then be able to improve the early detection of tumors in the long term.

The earlier cancer is detected, the better it can be treated. Blood tests should detect signs of cancer at an early stage - and with little effort. Research into this is in full swing.The more people of the global society find out about these investigations and the more experts will be found around the world, the faster progress will be made and goals will be achieved.


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