Breast cancer: genetic testing saves unnecessary chemotherapy
Dr. Andrea Bannert has been with since 2013. The doctor of biology and medicine editor initially carried out research in microbiology and is the team's expert on the tiny things: bacteria, viruses, molecules and genes. She also works as a freelancer for Bayerischer Rundfunk and various science magazines and writes fantasy novels and children's stories.
More about the experts All content is checked by medical journalists.Chemotherapy is a heavy burden - it is only then that many patients feel really sick. Sometimes the therapy would not be necessary at all. But that is often difficult for doctors to assess. A genetic test could help here.
When it comes to deciding “chemotherapy or not?”, Doctors have so far relied on certain characteristics of the cancer. These include tumor size, tissue peculiarities or the number of affected lymph nodes. However, it is not always possible to derive a clear recommendation from this, especially for women with early breast cancer. For 20,000 female patients a year, these conventional criteria produce a contradicting picture.
Reading in the genetic material
Another decision-making aid has been available for a number of years: so-called gene expression tests. They measure whether certain marker genes are active in the tumor tissue. To do this, laboratory diagnosticians obtain genetic material from a sample taken for the test or during the operation and read out the genes with a sequencer.
In some cases it can be concluded from this whether chemotherapy would be effective at all for the respective tumor. In addition, the laboratory doctors can calculate the so-called RS value (Recurrence Score) more precisely. It indicates the 10-year risk of relapse as a percentage. However, even with this test, the results are not always clear. Because many gene variants are not yet known.
Long-term studies are missing
Because gene expression tests are still a very young diagnostic method, there are still no long-term studies. Previous studies only consider a follow-up period of five years. "That is very short, because new tumors or metastases in breast cancer often only appear after ten to 15 years," explains Prof. Achim Wöckel, Director of the Women's Clinic at the University Hospital in Würzburg.
Nevertheless, the German Cancer Society has now included the gene expression tests in the new guidelines for breast cancer therapy.These are treatment standards that doctors use to align therapy. Genetic tests are recommended when the classic parameters and markers are not sufficient to decide whether chemotherapy makes sense.
The Institute for Quality and Efficiency in Healthcare sees it differently. The experts judge: Whether the test actually makes sense can only be finally clarified with the results of ongoing studies.
No final answer
The genetic tests did not provide a conclusive answer to all questions, stresses Wöckel. “A test like this is just one of the many ways in which you can decide how best to treat breast cancer.” And not every case requires a gene marker test. Often, conventional methods can be used to assess whether chemotherapy is necessary.
In certain cases, the costs for the genetic test are currently covered by the health insurance companies. However, there is still no uniform regulation on this.
Psychological factors
Chemotherapy is a standard method of treating cancer. "Chemotherapy rarely causes long-term physical damage," says Wöckel. In two to three percent of patients, it damages the heart, kidneys or other internal organs. But Wöckel emphasizes the psychological factors. The treatment is associated with hair loss and fatigue. Many patients then experienced stigma from others.
