Cancer: new genetic blood tests increase success rates in diagnosis and treatment

A liquid biopsy in Germany is a blood test that shows promising results in detecting small particles of cancer DNA in whole tumor cells in the patient’s blood. In the future, scientists and physicians propose to use such methods to assess the effectiveness of treatment, tumor monitoring and early diagnosis.

To determine if the tumor has returned after treatment, doctors rely on CT scans or additional biopsies. A routine biopsy is performed by cutting out a tumor particle, but researchers in labs in Germany are currently testing an innovative technique that could transform this approach. It’s called «liquid biopsy» and is a blood test which has only recently become possible due to the development of the latest extremely sensitive technology. This test shows promising results in detecting small particles of cancer. DNA in the patient’s blood or tumor cells.

The procedure consists only of drawing blood, which is much less burdensome for patients than a traditional biopsy or CT scan, so that oncologists can quickly determine whether a treatment is working and monitor whether it is developing resistance. Failed treatments can then be changed quickly, sparing patients from serious side effects and allowing doctors to try alternatives.

Scientists hope that in the future the method could even be used for very early diagnosis, but warned that further evaluations of the accuracy and reliability of the test are needed. So far, only small studies have been carried out on some cancers, including lung, colon and blood cancers. But the early results are encouraging. A National Cancer Institute study of 126 patients with the most common form of lymphoma found that the test captures recurrences more than three months before they are visible on CT scans.

Liquid biopsy in Germany also identifies patients who don’t benefit at all from therapy.

The idea behind the test comes from a discovery made a few years ago when studying embryos: they secrete small pieces of DNA into the blood of expectant mothers. It turns out that all growing cells, including tumors, secrete small fragments of DNA.

Standard methods of assessing the effectiveness of treatment have serious shortcomings. Doctors routinely monitor patients for symptoms such as pain or shortness of breath, but some patients do not pay attention to the manifestation of these indicators of their condition. In those patients who do note the symptoms listed above, they may remain long after the cancerous growths themselves have died. Therefore, pain and shortness of breath may indicate the condition of the human body, but not the condition of the cancerous tumor itself.

Patients are often tested with a scanner to determine if the tumor is shrinking, but it may take weeks or months before the tumor reports this shrinkage, in part because the scanner shows not only the tumor but also connective tissue, immune system cells, and signs of surgery. Thus, doctors can be misled into thinking that the tumor still exists when it has actually disappeared.

Blood tests also allow regular monitoring of tumors, but it does not show whether they are growing and mutating or developing resistance to treatment. The only other informative way to know about the status of the tumor mass and the effectiveness of the treatment is by Liquid biopsy. 

Another possible use of liquid biopsy is for early diagnosis of cancer. This is a more complex process. Because if a blood test shows the presence of cancer DNA or tumor cells, questions arise: where is the tumor, how can we detect its location, and is it worth starting treatment early? Some cancers stop growing or disappear on their own. In other cases, the outcome is just as good if the cancer is detected later and treatment is started accordingly later.

Two Australian scientists working with Dr. Bert Vogelstein at Johns Hopkins Hospital wondered if blood DNA testing for cancer could be prognostic. They conducted a study of 250 patients for blood cancer DNA after surgery. 80% of the patients in whom circulating DNA was detected had recurrences.

The cost of a liquid biopsy in Germany is 4,200 €.

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