Liquid biopsies, or blood tests that detect cancer by spotting tumour-associated mutations in DNA sequences found floating freely in the blood, have proved revolutionary. But these are largely designed to detect a single type of cancer. However, as per trial findings published in Science, a new blood biopsy can tell eight different types of cancer, by not just tracking DNA mutations but also abnormal levels of certain proteins in blood. The test was able to spot cancer in about 70% of more than 1,000 test subjects who had already been diagnosed. Liquid biopsies face a key challenge: Small tumours don’t release as much mutated DNA into the bloodstream as larger ones. Thus, detecting cancer relatively early is very difficult with liquid biopsies. False positives are a problem too, causing the subject severe stress and even exposing her to unnecessary and potentially dangerous medication. Oncologist Nick Papadopoulos at Johns Hopkins Kimmel Cancer Centre in the US and his team of researchers were aiming at developing a test that could detect cancers early, at a stage where treatment is easier and chances of cure are higher, and minimising false positives.
They ended up creating CancerSEEK, which not only examines mutations in 16 different genes, but also detects the level of eight different cancer-associated proteins—this could help catch the disease early. CancerSEEK’s effectiveness, though, varies as per the type of cancer. It detected 98% of ovarian cancer but couldn’t detect beyond a third of breast cancer cases. It could also identify the organ where the disease had taken root in 63% of patients. It did expectedly better at catching the disease at a later stage—78% detection at Stage III levels compared with 43% detection at Stage I. The Johns Hopkins researchers are planning to test CancerSEEK further, on 10,000 seemingly healthy subjects to refine findings. The test will certainly bring down cancer diagnostics costs by provind a one-stop shop for detection of multiple cancers, and if early-detection results improve, could catalyse a meaningful drop in cancer deaths.