Researchers have developed a noninvasive blood test based on combined analysis of DNA and proteins that may allow earlier detection of eight common cancer types. In more than 1,000 patients, their method, dubbed CancerSEEK, detected cancer with a sensitivity of 69 to 98% (depending on cancer type). Diagnosing cancers earlier - before they have metastasized - is one of the keys to reducing future cancer deaths. Here, Joshua Cohen and his colleagues developed a noninvasive blood test for cancer that assesses mutations in 16 cancer genes as well as the levels of ten circulating protein biomarkers. They studied 1,005 patients who had been diagnosed with Stage I to III cancers of eight common types, as well as 850 healthy control individuals, and found that CancerSEEK detected cancer with a sensitivity of 69 to 98%, depending on cancer type. The test was 99% specific, meaning that the likelihood of a healthy individual receiving a false positive result was very low. In some cases, the test also provided information about the tissue-of-origin of the cancer - a feat that has been difficult in past. The patients studied by Cohen and colleagues, it should be noted, had already been diagnosed with pre-metastatic cancer on the basis of disease symptoms. The ultimate goal of CancerSEEK is to detect cancer even earlier -- before the disease is symptomatic. The researchers estimate that the cost of this single blood test for eight cancer types may be less than $500, which is comparable to or lower than current screening tests for single cancer types (e.g., colonoscopy for colon cancer).