The chances of being cured of breast cancer have increased in recent decades, however if the tumour has metastasized, the disease remains essentially incurable. One reason for this could be that the metastases are detected late, after they have grown enough to cause symptoms or be seen on a radiological scan. If they could be found sooner, it might be possible to treat the new tumours.
Research findings, published in the journal EMBO Molecular Medicine, now provide new hope for a way of detecting metastases significantly earlier than is currently possible. The discovery is based on what is known as cell-free circulating DNA - small fragments of genetic material from different cells which circulate in the blood. It is normal to have low amounts of such DNA material in the blood, but in the case of diseases such as cancer, these amounts can increase. Furthermore, in cancer patients, the circulating DNA contains the genetic mutations which are specific to the tumor.
The researchers used samples from surgically removed tumours from patients with non-metastatic disease as well as blood samples taken from the patients at regular intervals during the years in which they were followed up. The tumour samples contained many genetic changes, which constituted a "fingerprint" specific to each tumour. Researchers then looked in the blood samples for circulating tumour DNA (ctDNA) with the same fingerprint.
Although the study is fairly small - it is based on material from only 20 women - the results are striking. For 19 of the 20 women, the ctDNA in the blood samples gave a clear indication of how things would turn out. The women who never got a relapse had no detectable ctDNA, whereas all women who had tumour DNA in their blood eventually had symptomatic relapses that were diagnosed in the clinic.
The metastases were also reflected in the blood samples at an early stage. There it was possible to find signs of the new tumours many months before hospital investigations revealed that the patients had suffered a relapse. On average, the circulating tumour DNA values in the blood samples identified the metastases 11 months before they were diagnosed by standard clinical procedures. In some cases, the blood test detected the metastasis three years earlier.
In addition to the possibility of treating women who are about to get metastases, a potential future use of the new method could be to determine which women do not need to be treated so aggressively. If we know that women with no ctDNA in their blood are not going to get a relapse, less aggressive treatment could be sufficient in their case. It is believed that many women with breast cancer are being overtreated, which entails considerable side effects. Currently, most breast cancer patients are treated not only with surgery, but also radiation, hormone therapy or chemotherapy.
The researchers have already started new studies in which a larger number of women will be monitored from breast cancer diagnosis and onwards, as well as testing ctDNA methods in other cancer types.
Based on material originally posted by Lund University.