Source: online.wsj.com Author: Ron Winslow In a fresh advance for the burgeoning field of personalized medicine, researchers have developed a blood test based on the DNA of tumors that could help tailor treatment for individual cancer patients. The report, announced Thursday, represents one of the most tangible examples yet of how the ability to sequence a person's entire genetic code could have a direct impact on patient care. There have been a flurry of reports on new sequencing technology that is yielding enormous amounts of information about genetics and disease, but that has yet to deliver much in the way of new treatment strategies. "For cancer patients there hasn't been much utility so far. This may prove to be one of the first useful approaches," said Victor Velculescu, co-director of the cancer biology program at Johns Hopkins University's Kimmel Cancer Center and senior author of the new study. Much research involving whole-genome sequencing is aimed at finding differences in the individual letters that make up the genetic code. The belief is that those small alterations will point to molecular pathways that regulate disease, which would be potential targets for drug therapies. The Hopkins researchers, writing in the journal Science Translational Medicine, took a different approach. They scanned the DNA of tumors taken from six patients with breast or colon cancer, looking not for tiny DNA changes, but what they call rearrangements in large sections of the genome of tumor cells. The DNA of tumors varies genetically from that of normal [...]