Scientists Spot Genetic Traces of Individual Cancers

Scientists Spot Genetic Traces of Individual Cancers.
Researchers have found a modus operandi to analyze the speck of a cancer, and then use that trace to track the trajectory of that particular tumor in that particular person. "This facility will allow us to measure the amount of cancer in any clinical specimen as soon as the cancer is identified by biopsy," said reflect on co-author Dr Luis Diaz, an assistant professor of oncology at Johns Hopkins University.

And "This can then be scanned for gene rearrangements, which will then be second-hand as a template to track that exacting cancer." Diaz is one of a group of researchers from the Ludwig Center for Cancer Genetics and Therapeutics and the Howard Hughes Medical Institute at Johns Hopkins Kimmel Cancer Center that sign in on the idea in the Feb 24 issue of Science Translational Medicine. This latest finding brings scientists one motion closer to personalized cancer treatments, experts say.

But "These researchers have determinate the entire genomic sequence of several breast and colon cancers with great precision," said Katrina L Kelner, the journal's editor. "They have been able to connect small genomic rearrangements single to that tumor and, by following them over time, have been able to follow the course of the disease." One of the biggest challenges in cancer care is being able to see what the cancer is doing after surgery, chemo or radiation and, in so doing, help guide therapy decisions. "Some cancers can be monitored by CT scans or other imaging modalities, and a few have biomarkers you can follow in the blood but, to date, no infinite method of accurate surveillance exists," Diaz stated.

Almost all anthropoid cancers, however, exhibit "rearrangement" of their chromosomes. "Rearrangements are the most dramatic form of genetic changes that can occur," lucubrate co-author Dr Victor Velculescu explained, likening these arrangements to the chapters of a enlist being out of order. This type of mistake is much easier to recognize than a mere typo on one page.

But habitual genome-sequencing technology simply could not read to this level. Currently available next-generation sequencing methods, by contrast, authorize the sequencing of hundreds of millions of very short sequences in parallel. For this study, the researchers old a new, proprietary approach called Personalized Analysis of Rearranged Ends (PARE) to analyze four colorectal and two teat cancer tumors.

First, they analyzed the tumor type and identified the rearrangements, then tested two blood samples to verify that the DNA had been focus into the blood, sort of like a tumor's trail of bread crumbs. "Every cancer analyzed had these rearrangements and every rearrangement was solitary and occurred in a different location of genome. No two patients had the same call for rearrangements and the rearrangements occurred only in tumor samples, not in normal tissue".

So "This is a potentially very sensitive and specific tumor marker". Levels of the biomarkers also corresponded with the waxing and waning of the tumor. "When the tumor progresses, the germane amount of the rearrangement increases in the blood and goes down after chemotherapy. It tracks very nicely with the clinical retelling of the tumor."

The method would not be used for cancer screening and more experiment with needs to be done to make sure PARE doesn't detect low-level tumors that don't in fact need any treatment. Although this approach is currently expensive (about $5000 versus $1500 for a CT scan), the authors foretaste that the cost will come down dramatically in the near future, making PARE more cost-effective than a CT scan here. Under the terms of a licensing agreement, three of the survey authors, including Velculescu, are entitled to a dispensation of royalties on sales of products related to these findings.