Using a Urine Sample to Diagnose Breast Cancer

Catching breast cancer early in more women: That is the goal of assistant professor Dr. Thalia Erbes from the Department of Obstetrics and Gynecology at the Freiburg University Medical Center. She and her team in the project MAMMACHECK are working to verify the promising results of a pilot study for a new urine test. This new test detects specific microRNAs, which means it relies on different biomarkers than those normally used in diagnostic procedures. Should their study be successful, major laboratories could be able to offer the test in just a few years.

“The earlier cancer is detected, the better the chances of recovery and the more we can avoid using aggressive treatments on patients,” says Dr. Thalia Erbes about the diagnosis of breast cancer. Photo: Axel Kock/stock.adobe.com

Could testing for breast cancer soon be as easy as taking a pregnancy test? “Our diagnostic test also works with urine,” says Dr. Thalia Erbes, who wears many hats as the medical director of Breast Health at the Department of Obstetrics and Gynecology, the head of the breast screening center MVZ Brustzentrum GmbH, and the director of the Research Laboratory for Molecular Oncology, all at the Freiburg University Medical Center. In the three-year-long MAMMACHECK project, Erbes and her team are working to get their new breast cancer test ready to bring to market. The test is not intended for use at home, and it does not detect pregnancy hormones. Instead, it detects so-called microRNAs. “The uncomplicated, pain-free test is meant as an aid in preventative care,” Erbes says. The test has the potential to catch more cases of early-stage cancer than is currently possible, meaning it could also make treatment less invasive.

Reducing the Known Disadvantages

“Breast cancer is the most common type of cancer in women,” Dr. Erbes says. Mammography is the gold standard for breast cancer diagnosis. For this x-ray procedure, called a mammogram, the patient’s breasts are pressed flat between two Plexiglas plates. “Many women find this uncomfortable or even painful,” Erbes says. The majority of women affected by breast cancer are over 50 years old, yet almost half of the women in this age group choose not to have a mammogram because of the discomfort and exposure to radiation. A mammogram is also less reliable for screening the denser breast tissue of younger women. “Yet, we know that they also often develop breast cancer. Three out of ten breast cancer patients are below 55 years old,” says Erbes.

All of these disadvantages could be avoided with a urine test that is pain-free and quick. “The patient only has to supply a urine sample,” says Erbes. She predicts that considerably more women of all ages would take the urine test. This would enable breast cancer to be detected in more patients and at an earlier stage than is currently the case. “The earlier cancer is detected, the better the chances of recovery and the more we can avoid using aggressive treatments on patients,” the doctor explains, adding: “However, the urine test won’t replace a mammogram.” This standard procedure will continue to be necessary – for example, to determine the size of a tumor in a patient who has tested positive. As Erbes says, “Our test has the potential to become an integral part of breast cancer prevention, provided the reliability of MAMMACHECK is validated.”

The new urine test targets miRNAs, or microRNAs. These are short RNA nucleic acids – in other words, sister molecules of DNA. “All cells produce miRNAs,” says Markus Jäger, the lab’s technical director in the MAMMACHECK project. When a gene becomes active, a kind of copy is created in the transcription process: This copy is the mRNA (messenger RNA). A compatible miRNA can bind with the mRNA with the result that the ability of cells to translate the bound mRNA into a protein is repressed or completely obstructed, as opposed to unbound miRNA. “When comparing the urine of healthy women to that of women who have breast cancer, we discovered miRNAs that are specific to breast cancer,” says Jäger.

The Pilot Study Gives Reason to Hope

The development team selected a combination of four breast cancer miRNAs for a small pilot study. Urine samples were then taken from healthy women as well as women with smaller and larger tumors – in other words, women who have early and later stages of cancer. The study did not include patients with metastases. “In the pilot study, our test produced a sensitivity rate of 98.6 percent and a specificity of 100 percent,” says Erbes. The test missed less than two out of one hundred breast cancer cases, and it did not produce any false positive results in any of the healthy participants. “Now we are moving on to validation for MAMMACHECK,” Erbes says. This means that the very promising results of the urine test have to be validated by a large number of patients. The Department of Obstetrics and Gynecology and the breast screening center MVZ Brustzentrum GmbH want to recruit 1,500 women for the study.

Jäger’s laboratory is responsible for processing all of the test samples. “I won’t know which urine samples are from healthy women and which are from women with breast cancer,” he says. Jäger is working together with Roland Zengerle, Professor for MEMS Applications at the Department of Microsystems Engineering (IMTEK) at the University of Freiburg, to automate the procedures for processing the lab tests. The first step is to isolate the microvesicles in which the miRNAs are packaged, then to isolate the miRNAs themselves. “Only a very limited amount of these can be extracted from urine. We’re talking in the lower nanogram range,” he says. The miRNAs are then run through standardized procedures, beginning with all miRNAs being transcribed into DNA copies, after which the breast cancer markers can be detected through the established and highly specific method of polymerase chain reaction, or PCR. The only process that must still be done manually is the isolation and breaking open of the microvesicles.

“Eventually, a single machine will probably be able to carry out all of these steps automatically, one after the other,” says project coordinator Dr. Frank Fuchs, a physicist who is also conducting the market analysis for MAMMACHECK. Fuchs served as a research group leader at the Fraunhofer Institute for Applied Solid State Physics (IAF) for 30 years and has many years of experience collaborating with partners in industry. “I’m talking to major laboratories about what devices could enable the best possible launch,” he says. The miRNA urine test still has to pass the validation phase, however. “Both the cost and labor-intensive study and the automation pose a great financial risk,” Fuchs says, adding: “Private investors would not likely finance such a project.” MAMMACHECK is currently funded by the Federal Ministry of Education and Research. “This also ensures that our study has higher quality,” he says, adding: “The study is reviewed by an independent body without any conflicts of interest with investors.”

The New Principle May Hold Additional Potential

The Clinical Trials Unit at the Freiburg University Medical Center is supporting the project team in the analysis and management of data. If all goes well with the project, a demonstration prototype will be ready in three years, after which a final prototype will be set to go into mass production. But this does not mean that the full potential of miRNA will have been realized. “Perhaps it could lead to a new way to monitor the treatment of tumors?” Fuchs speculates. “We could try using it to detect the recurrence of cancer,” adds Jäger. “Perhaps it’s possible to use our or other miRNA markers to predict how well patients will respond to certain therapies,” suggests Erbes. MAMMACHECK may turn out to be only the beginning of a new development through which hopefully many women will be spared a great deal of suffering.

Jürgen Schickinger