New research into "liquid biopsies" is promising, but there's still not proof they can find cancer in a healthy person. The “Cancer Moonshot” mission, the federal project with the ambitious goal of doubling the rate of progress of cancer research, which despite more than $100 billion in government spending since the 1970s didn’t really make a big difference in the overall cancer death rate in the US, may seem simply a new name for the same daunting challenge but has a much better chance of success. Not only do scientists now have a clearer understanding of the complexities of the disease and a realization that there is no one cure for all cancers, but they also have the benefit of supercomputers that can analyze an enormous amount of cancer research and the mapping of the human genome.
The latter has opened up promising avenues of treatment, such as new bio-technology that creates immune cells to fight cancer, and more precise treatments based on a patient’s DNA. At the same time, real progress is being made on another key front the ability to detect traces of cancer in a person’s body without needing to do something as invasive as a conventional biopsy. The process, known as a liquid biopsy, involves only drawing blood from a patient.
Floating cancer DNA
What tips off the presence of cancer are fragments of mutated DNA released by tumor cells into a person’s bloodstream. These can be found by scanning the blood through a gene-sequencing machine. Since early detection has long been considered a key to surviving cancer, scientists are hopeful a blood test that lets doctors know cancer is present before it begins to spread could make a big difference in the number of people who beat the disease.
Earlier this month, a team of researchers from Johns Hopkins University and the Walter and Eliza Hall Institute of Medical Research in Australia published a study suggesting that they could pretty accurately predict if a colon cancer patient would have a recurrence of the disease. After doing a series of liquid biopsies on 230 patients over two years, they found that 79 percent of the patients whose blood still had traces of tumor DNA after surgery suffered a relapse. These were all patients with stage 2 colon cancer that had not yet metastasized. The test wasn’t perfect. Almost 10 percent of the patients who didn’t appear to have tumor DNA in their blood had their cancers come back. Still, the scientists said the liquid biopsies could provide a strong indication as to whether a patient was cured through surgery or if he or she also needed to be treated with chemotherapy to take care of cancer traces that remained.
Last month, at the American Society of Clinical Oncology conference in Chicago, researchers presented the largest study yet of liquid biopsies, reporting that blood tests to detect cancer mutations largely agreed with what was found through conventional biopsies. In that case, the scientists analyzed more than 15,000 liquid biopsies that had been performed by Guardant Health, a Silicon Valley startup.
Those blood samples came from patients with several different types of cancer, including lung, breast and colorectal. For about 400 of those patients, there were also tumor tissue samples. When the blood samples and tissue samples were compared, the researchers found the same cancer mutations in both more than 90 percent of the time. Those impressive results were for a gene mutation associated with tumor growth. There was less agreement between the two types of biopsies, however, when the scientists analyzed mutations that indicate potential resistance to certain drugs. Also, for about 15 percent of the patients overall, the liquid biopsies didn’t show any evidence of the tumor.
This recent research does boost the prospects for liquid biopsies, but the tests still have a long way to go before they’re considered reliable enough to replace more invasive biopsies. So far, studies have involved samples from patients who were already known to have cancer. That suggests liquid biopsies could be useful in monitoring tumors to determine if a treatment has been effective.