Screening melanoma patients’ blood could allow doctors to predict chances of cancer relapse. According to a new study published in Cancer Discovery, researchers were able to track relapse events based on sequencing of tumor DNA that’s in the bloodstream. A blood test based on this discovery could offer doctors and patients a way to stay ahead of melanoma’s penchant to escape treatments.
One of the biggest challenges in treating melanoma, skin cancer, is the high probability of relapse after initial treatment success. In about 50% of melanoma cases, the cancer is caused by an activating mutation in the BRAF gene that signal cells to grow and divide uncontrollably. Patients who receive drugs that specifically inhibit BRAF initially respond quite well, but many of those patients inevitably suffer relapse as the cells adapt and acquire new mutations. In these situations, early detection of new mutation events could impact the outcome of patient survival.
Circulating tumor DNA (ctDNA), also known as cell-free tumor DNA, is genetic material that’s freely floating in the bloodstream of cancer patients. Dead tumor cells are the source of ctDNA, as when broken these cells release the tumor DNA into the patient’s blood. ctDNA represents a non-invasive cancer biomarker that can indicate the presence of disease. And because detection requires only a blood sample, the technique of using ctDNA for cancer diagnosis is often called “liquid biopsy."
In blood samples from seven advanced melanoma patients, researchers from the Cancer Research UK Manchester Institute found new mutation patterns in genes other than BRAF. Specifically, the ctDNA revealed mutations in oncogenes like NRAS and PI3K, which are involved in the cell division process. These new genetic mutations are cancer’s escape routes against drugs that only target the BRAF gene, thus enabling melanoma’s relapse.
"Being able to spot the first signs of relapse, so we can rapidly decide the best treatment strategy, is an important area for research. Using our technique we hope that one day we will be able to spot when a patient's disease is coming back at the earliest point and start treatment against this much sooner, hopefully giving patients more time with their loved ones. Our work has identified a way for us to do this but we still need to test the approach in further clinical trials before it reaches patients in the clinic," said Professor Richard Marais, lead study author and Cancer Research UK's skin cancer expert.
A blood screen specific for melanoma relapse has not yet been developed for the clinic, but the researchers are optimistic “blood tests like these will help us to stay one step ahead in treating cancer.”
Additional source: EurekAlert!