Dennis Lo, professor of medicine and chemical pathology at the Chinese University of Hong Kong, was the first to discover the presence of fragmented fetal DNA in the maternal bloodstream, thereby becoming the pioneer of non-invasive prenatal diagnosis. This finding, first made in 1997, has led to a much safer and simpler screening test for Down syndrome. To date, more than one million pregnant women have been tested. He is now repeating this scientific and commercial success by developing cancer-screening tests based on a simple blood test. Dying cancer cells also shed DNA into blood but the amount of this DNA is very small and is obscured by the healthy DNA that circulates in the bloodstream. The approach relies on gene-sequencing machines, that rapidly decode millions of short fragments of DNA that are loose in the bloodstream. The results are then compared with a reference map of the human genome. Researchers can then identify the specific patterns of rearranged DNA that are indicative of a tumor.
In addition to screening for cancer, liquid biopsies could be helpful in identifying specific DNA mutations in people already fighting the disease. For instance, 40% of Chinese lung cancer patients have a mutation in one gene, EGFR, which, if identified at the right stage, can make them eligible for targeted drugs.
Currently, the cost of a DNA test for liver cancer is too high for routine use but fetal tests were similarly expensive at first and gradually, the prices declined to as low as $800 leading to much wider use. Jay Flatley, CEO of Illumina, the San Diego company that builds next generation sequencing machines, says that the market for such tests could be worth at least $40 billion and that company would begin offering researchers a liquid-biopsy test kit to facilitate the search for signs of cancer.
Cancer is among the leading causes of death worldwide. With an estimated detection rate of 22 million new cases in the next two decades, the development of the ‘Liquid Biopsy’ technology is a major breakthrough in cancer prevention research. Cancer, when detected at advanced stages, is largely untreatable. Early detection has been met with most notable success in reducing deaths from common cancers (like colonoscopy examinations in colorectal cancer). This test has been quite successful in major liver and throat cancer studies that were recently conducted in China and it has the potential to be converted into a general-purpose test for nearly any cancer. An annual, noninvasive blood test will soon be able to detect cancer while it’s curable.
