Almost two months ago, the Heidelberg University Hospital made global headlines with a “milestone in the early detection of breast cancer”. Prof. Dr. Christof Sohn, Medical Director of the University Women’s Hospital, explained: “The blood test developed by our team of researchers is a new, revolutionary method for non-invasive and rapid detection of breast cancer using biomarkers in the blood and could become marketable this year.”
According to the research team at the University of Heidelberg and a subsidiary company of the University Hospital, HeiScreen GmbH, in which two members of the research team are also financially involved, the new method is “significantly less harmful for women because it is neither painful nor involves radiation exposure”. The fact that the head of the test development team, molecular biologist Rongxi Yang, left the University Hospital in 2017 and that the subsidiary company of the University Hospital has a stake in Heiscreen NKY GmbH, which is responsible for test marketing in Asia, was also surprising.
At the end of March, the hospital rowed back and apologised for the PR campaign. The reason: HeiScreen GmbH lacked evidence and public results from clinical studies that the blood test works at all, and information about how many false positive test results were found in healthy volunteers.
A few days ago, the public prosecutor’s office in Heidelberg started preliminary investigations after the University Hospital filed a criminal complaint against unknown individuals. “As a public institution, the University Hospital sees itself obliged to take this step because of signs of an unfair procedure in the development and announcement of the potential blood test for breast cancer diagnostics, which was presented to scientific experts and the public on 21 February,” said the responsible authorities in a statement. The University Hospital itself had “already taken extensive measures to deal with the situation: An internal scientific working group and the clinic’s internal audit department are responsible for analysing the processes and report directly to the Executive Board. An external neutral expert commission is being formed.”
No substitute for mammography and co.
The test, which is based on so-called “Liquid Biopsy”, was designed to detect breast cancer using biomarkers in blood, urine or saliva and, in the long term, replace conventional methods such as mammography screening or MRI. The basis of the test is that genetic material changes as soon as a healthy cell mutates into a cancer cell, which in turn produces specific biomarkers. These biomarkers are located on the surface of the tumour cell and are separated from the surface when the tumour cell sinks, for example. This enables them to enter the bloodstream and be detected in the blood serum.
In the Heidelberg research project, the blood of healthy women as well as women with breast cancer was tested for the presence of different biomarkers (mostly protein components) that occur in different forms of breast cancer and examined for typical cancer mutations.
The detection of these so-called biological tumour markers (“biomarkers”) is carried out by means of molecular biological methods. The markers, which have so far been tested on tumour tissue in clinical practice, enable the identification of the characteristics of a tumour that has already been diagnosed: on the one hand, they enable assessment of the malignancy of the tumour and its treatment prospects (= predictive value) and, on the other hand, they provide information on the effectiveness of a targeted therapy (= prognostic value). Examples of such biomarkers are the hormone receptor status, which provides information on the use of anti-hormonal treatment, or the Her2 receptor status, which provides information on a stimulating growth factor for tumour cell division.
In theory, the new test sounds promising, but there are still some questions about its general usability. Firstly, there is not just one type of breast cancer, but a wide range of biologically different types that are diagnosed at different stages of the disease. The so-called “invasive breast carcinomas” alone are subdivided into ductal (concerning the milk ducts), lobular (concerning the mammary glands) and other less frequent variants, with ductal carcinomas being the most frequent with 70 to 80 percent. In addition, there is the DCIS (ductal carcinoma in situ), an early form of breast cancer in the milk ducts, which has not yet spread into the surrounding tissue (= non-invasive), but for which there is a risk of developing into cancer (=invasive carcinoma).
Low probability of detecting cancer cells
The report from the University Hospital in Heidelberg gives the impression that blood tests and special molecular biological examinations can be used to detect a previously undiagnosed malignant breast tumour. Without the necessary background information, this might suggest that a tumour cell that happens to flow past in the blood test can be picked up and the tumour can be detected. This misconception is easily refuted: in a blood test, a 5-10 ml blood sample is taken. There are 4-5 litres of blood in a woman’s body. It is therefore quite unlikely that a certain tumour cell will pass by exactly at the moment the blood is taken. Therefore, the probability that cancer cells could be identified as such in a test of this kind is very low.
Although the idea of a blood test, as presented by the University Hospital in Heidelberg, is excellent in the eyes of many physicians, it must first be thoroughly tested for its practical use. As the University Hospital recently confirmed, 30 women were falsely tested positive for breast cancer in 100 examinations, while the cancer was not always detected in those suffering from the disease.
So it will take some time before this type of blood test is suitable for general use. However, physicians find it surprising and ethically questionable that a renowned institution such as the Heidelberg University Hospital allows a faux pas of this magnitude and gives false hope to millions of women by presenting an inadequately tested method to the public without thorough proof.
According to figures published by the German Cancer Society, breast cancer is the most common cancer among women in industrialised countries, accounting for about 30.5 percent of all cases. In Germany, more than 70,000 women are diagnosed with breast cancer and almost 20,000 die from it every year.
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